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💾 Iso Prep Download the iso and check the gpg signature via the website mount the iso in a usb via something like balena etcher 🚀 Launch Install make sure the bios have the disable and boot on the iso secure boot 🎹 Set Up the Keyboard Layout By default the layout is set to . US If you want to list all the layouts available do . ls /usr/share/kbd/keymaps/**/*.map.gz Use a layout with, for example, (here German layout). loadkeys de-latin1 🛰️ Go to the Internet Wifi dosent work out of the box but ethernet yes Check your network interface name via . ip link Check the status of your wifi card with . If your card is blocked, unblocked them with . rfkill rfkill unblock your-card-id For the wifi connection you have to use the package. Hopefully arch include the package in the iso. iwd Open the prompt with and : iwctl list all your device with device list launch a scan station [device name] scan get the list of the available network station [device name] get-network connect to the network with station [device name] connect [SSID] enter the password check the connection with and station [device name] show ping archlinux.org done :) automatically stores network passphrases in the directory and uses them to auto-connect in the future. iwd /var/lib/iwd 🕛 Update System Clock Just do . Check the service status with . timedatectl set-ntp true timedatectl status 💽 Disk Partitioning warning : this step erase all the data in your disk if you confirm the operation ! List your drive with and note the one you want to use. fdisk -l Open the prompt on the right disk with . fdisk /dev/[your disk] remind to delete the old partition before the following command.
Do that with command and the id of the partition. d Let's create the partition, in the open fdisk prompt : Here we create a gpt partition because I do a EFI install create a new gpt label with g add the first partition with (efi) n partition number is 1 the first sector is the default one (just hit enter) the last sector is for 550mb +550M add the second partition with (swap) n partition number is 2 the first sector is the default one the last sector is (handle the size of your swap like you want, minimum 2gb is ok) +4G add the last partition with (primary/data) n partition number is 3 the first sector is the default one the last sector is the default one Ok now we need to change the partition type with the command : t chose for partition the type (list all the partition type with if your are not sure 1 1 L chose for partition the type 2 19 don't change the partition 3 Just enter to write the partition table. w 🗃️ Make the File System For the efi partition, we need to have a FAT32 file system, do it with mkfs.fat -F32 /dev/[your partition 1] For the swap we need a swap filesystem, do it with mkswap /dev/[your partition 2] and activate the swap with swapon /dev/[your partition 2] For the main partition we do a ext4 filesytem : mkfs.ext4 /dev/[your partition 3] ⚡ Mount the Big Partition in the Live Environment Simply do mount /dev/[your partition 3] /mnt 🧬 Install the Base System We do it via .
Here is the arch system, the kernel. pacstrap /mnt base linux linux-firmware base linux 🧫 Generate the fstab Simply do . genfstab -U /mnt >> /mnt/etc/fstab 🔑 Log to the Newly Installed Arch Do . arch-chroot /mnt 🌍 Set the Timezone here the region and city is in the file /usr/share/zoneinfo do ln -sf /usr/share/zoneinfo/_Region_/_City_ /etc/localtime and generate with /etc/adjtime hwclock --systohc 🏴‍☠️ Set the Locale you need to install nano if you want to use it Edit the file , and uncomment the good option for you. locale.gen nano /etc/locale.gen For example for the generic qwerty. en_US.UTF-8 UTF-8 And generate the local with . locale-gen Add the following line to : . /etc/locale.conf LANG=en_US.UTF-8 👽 Set the Hostname and the Host Just add the wanted hostname in . /etc/hostname For the host open and add the following line : /etc/hosts 127.0.0.1 localhost
::1       localhost
127.0.1.1 [your-hostname].localdomain [your-hostname] 🤓 Create the User set the password the root password with passwd create a user with useradd -m username set the password of the new user passwd username set the group for the user usermod -aG wheel,audio,video,optical,storage username 🎛 Install Sudo and Authorize the User to Use Wheel Group install with pacman -S sudo and open with and uncomment the line. visudo EDITOR=nano visudo %whell ALL=(ALL) ALL Here we use nano but if you want to use vi remove EDITOR=nano, if you don’t want nano nor vi replace nano with your loved one 📟 Install Grub and Basic Package just do pacman -S grub efibootmgr dosfstools os-prober mtools 🎬 Make the EFI Directory and Mount It Do and mkdir /boot/EFI mount /dev/[your efi partition] /boot/EFI 🪃 Init grub install grub (for efi) with grub-install --target=x86_64-efi --bootloader-id=grub_uefi --recheck create the config grub-mkconfig -o /boot/grub/grub.cfg 📦 The Other Stuff (Networking, etc...) Here we install the package, because after the final reboot the package will no longer be available. networkmanager iwd We install too. git pacman -S networkmanager git Enable network manager with . systemctl enable NetworkManager ♻️ Reboot Before reboot exit and unmount : exit
umount -R /mnt And ! reboot 📡 Reconnect WiFi after the Login If the ping command failed after the installation you need to relogin to your wifi. For that we use the previously installed package. nmcli Check if the radio is on with , if not open up with . nmcli radio wifi nmcli radio wifi on Check the wifi point with . nmcli dev wifi list Check your device with . nmcli dev status And connect with . sudo nmcli dev wifi connect [network-ssid] password [network-password] If you want to look all the saved connection do . nmcli con show 📽️ Video Driver For nvidia do pacman -S nvidia nvidia-settings nvidia-utils For other check the wiki 🎞️ Xorg Server Actually we use xorg but if you want another display server check the wiki Install with . xorg-server If needed install check the wiki to know if you need it. xorg-apps It usefull to install xmessage too . pacman -S xorg-xmessage 🧮 Base Devel for Makepkg Mandatory for the use of the AUR package Just do a pacman -S --needed base-devel 🍱 The Essential Package List of, my, essential package to have on a fresh install : unzip pacman -S unzip nerd font Warning: This is a large size repo clone the repo https://github.com/ryanoasis/nerd-fonts.git run for installing all the font ./install.sh bluetooth pacman -S bluez-utils paru (for easy gestion of the aur package) clone https://aur.archlinux.org/paru.git cd into the repo build it makepkg -si 🔏 Activate the Num Lock This method is good because is activate the numlock in the early bootup stage, usefull for the psw prompt in the full-disk encryption for example. Install the AUR package. mkinitcpio-numlock Add in the line (before encrypt if present) in . numlock HOOKS /etc/mkinitcpio.conf Usually between modconf and block ⁉️ And Now What? Now you have Arch and the minimum for booting correctly. All you have to do is install the window manager or the desktop environment you want! Check for information. the wiki page For example, if you want KDE : pacman -S plasma kde-applications If you want some tutorial stuff for XMonad I'm writing a story in a few days, wait for the update! Happy arching mate 🖖

Step-by-Step Guide to Installing Arch Linux 

The bitcoin and cryptocurrency space was once quite chaotic; in many ways, it still is. That’s not to say a little chaos is a bad thing. Often it’s the spark that results in impressive innovations. Many of the great ideas that have flooded out into the world and changed our perceptions result from great minds combined with chaotic ideas. However, it’s hard not to wonder if this spark has been washed away by the "men in suits". Has the dream of mainstream adoption and merely too much of what is or was arguably wrong with the traditional business world snuck in? Old Stories and Pipe Dreams The early days of bitcoin read like a peculiar mix of hope, enthusiasm, and potential with those sitting on the outside slowing, taking more notice of this oddity sitting on a knife’s edge, waiting to see which direction it fell. So many great stories came out of the early days. So many moments that probably didn’t feel all that significant at the time became rolling metaphorical balls of snow collecting headlines and drawing attention the more they began to matter to those affected by them in the years to come. Everything from the message hidden in the Bitcoin genesis block to bitcoin pizza day is now essentially lore to inside the community and fascinating oddities to those looking in from the outside. Even in recent years, there’s been this lingering dream of adoption by the masses, something that many people associate with the arrival of the traditional sectors in both finance and technology. Few things used to cause pumps like talk of vague partnerships with outsider companies or tech behemoths showing interest in a particular project. While more subtle, you could still see the buzz caused in recent months by the discussion of PayPal potentially adopting bitcoin in some fashion. When you step back and look at this growing desire to be part of the norm, does this shake off the early anarchistic and privacy-conscious roots of bitcoin and crypto, and if so was it inevitable all along? When did the outsiders want to become insiders? Was the dream too big at first that it felt more like an experiment than a potential reality where it didn’t matter until it suddenly did? It’s hard to say as even those around during these times will likely have subconsciously grown and adapted their views over the years. I’m not sure these questions even have a clear answer, but they do provoke curious thoughts. Stubborn Hearts and Minds Set on Freedom While looking back, it’s easy to lose track of what’s right in front of us and what’s been here all along. With this recent surge of interest and activity in decentralized finance (DeFi) alongside the seemingly ever-growing peer-to-peer (P2P) trading community, perhaps things haven’t changed so much after all. For a while, it felt like the race for the theoretical highest transactions per second, or chasing the various other hype trends that came and went was often the priority. Yet, many projects are now actively being built on. As a result of this shift from promising the world back to actually trying to change it again, some projects have begun developing bright and thriving ecosystems surrounding themselves. It’s easy to point to all the action happening on the Ethereum network right now. Still, it’s even more interesting to look to projects like Polkadot, Kusama, and other newer “blockchain canvases” and seeing everything that is evolving from those. Not to say bitcoin has lost its shine either. Every day that goes by, the security it bestows upon its users alongside the broad power it provides in terms of self custody makes a progressively louder statement. The pursuit of financial freedom isn’t always optional; it’s essential to thrive or even survive for many. It’s easy for a lot of us to forget this. One of the reasons it’s vital not to give away any more financial freedom and privacy than you need to is that it makes it harder for those already at a deficit somehow. Thankfully, this attitude is still strong among the many projects exploring decentralized governance, decentralized finance, P2P trading, and much more in the rapidly shifting and moving cryptocurrency scene. For many cryptocurrency users, freedom is being lost, but it hasn’t been lost entirely with privacy in a similar position. As time has passed it just takes more consideration about how you use cryptocurrencies to make the most of the potential they have to empower you in these areas. The P2P trading community started (at least in some ways) likely out of necessity. Still, it’s a community that has evolved along with increased adoption as more people every day are getting involved in crypto in one way or another. One P2P exchange in particular (and my recommendation) , is leading the charge forward exploring ways to continue providing as much freedom as possible by delving into new avenues like multi-custodial trading, and consistently increasing access to new payment methods to help retain the independence to authentically trade your way, whatever requirements you have, and whatever roadblocks you face. LocalCoinSwap Money isn’t Always Tied to Influence Just because you still hear rustling and chatter every time there’s talk of a sizeable non-crypto company or more traditional influencer entering the space, it doesn’t mean it moves the needle at the end of the day. Even though the men in suits can throw funding around, the amount of regulatory and internal red tape they often face trying to do so leaves them at the back of the crowd. Those making the real waves tend to be those that are here exploring new ground or are otherwise making a place for themselves. Some earn influence through their development efforts or sharing ideas, others through growing communities, and sometimes even simply through their experiences being exposed to the volatile and frequently chaotic nature of cryptocurrency. When a lot of those that have been in the community for some time have access to substantial funding of their own, there’s a strange power dynamic that I suspect will have been and continue to be a surprise to outsiders that try and buy their way into the forefront of cryptocurrency and end up instead having to settle for visibility where they can get it. Those projects pushing the boundaries of what’s possible with blockchain technology and the companies that continue to ensure that the important traits of the early days continue to evolve will often be far too much of a leap for the men in suits. In light of this, too much bureaucracy and the fear of new ideas will undoubtedly result in less dampening of the innovation that can and is occurring around us. Whether this just allows for more innovation before ideas get slowed or hampered by traditional oversight and pressure or it merely allows for more growth before the men in suits have much influence, in either case, it doesn’t seem like a bad thing. Bitcoin, cryptocurrency, and blockchain aren’t going away any time soon. Instead of waiting for your favorite conglomerate to get involved and attempt to sway your judgment of what matters and monetize yet another aspect of your life, look to those building, exploring, engaging with each other, trading P2P across not just borders but the world. Look at what matters now, so we retain our freedom to explore and exchange. Look ahead, so we don't lose that hint of chaos that has got us this far and will lead us to wherever it is we are going in the future.

Did the Men in Suits Ruin Cryptocurrency For The Rest Of Us?

The ATM can be considered a staple of traditional finance, even those in most developing countries have used one at some point or another. Scattered across the world are these hard-line connections between people and their bank accounts. With the introduction of cryptocurrency came many things, including the bitcoin ATM, but is it a hybrid of the old and new world or just a familiar idea that in the end will be a quirk in the history of bitcoin that slowly dies out. The Price of Convenience is Finite The bitcoin ATM always seemed to pride itself on being a tool of convenience and a link between cryptocurrency and something we already knew. The problem is that while convenience does indeed merit extra expense, this is something that requires a reasonable trade-off to make sense. Searching online for a map of bitcoin ATM locations, heading over to the nearest one, and buying bitcoin doesn’t sound so bad at first thought. However, once you consider the excessive fee structure typical of bitcoin ATMs, you have to put a price on that effort. For a while, you could factor in the lack of KYC & verification required to use a bitcoin ATM. This flexibility allowed you to buy your way in and out of the cryptocurrency markets without dealing with excessive verification or the risk of supplying your ID to companies existing in a new market that often derived some degree of chaos from the regulatory uncertainty of the times. Growth Doesn’t Necessary Reflect Value If you look at the rates of bitcoin ATM installations, it would be easy to assume they are a growing success, but the picture isn’t as straightforward as it seems. For many years suppliers of bitcoin and even just more general cryptocurrency ATMs were significantly limited, leaving the demand unable to be met by the supply of these devices. With the increased numbers of devices rolling out, this has likely started to alleviate in recent years as most problems of this nature do when the demand is there. I’d argue that this constant current growth in installations is merely an echo of this restricted supply’s dynamics being improved. As the ability to produce these devices becomes more mainstream (even in a niche context), the rate at which they can be sold and rapidly installed increases at a rate that looks like a success, but is it the parabolic pipe dream it seems? At least in my opinion, nope. The True Nemesis isn’t a Product of the Future Unlike many technologies that are replaced or superseded with something new, the bitcoin ATM will likely drown in an idea that predates it. In June 2012, the launch of LocalBitcoins brought P2P (peer-to-peer) trading into the homes of cryptocurrency traders worldwide, providing the flexibility and convenience that the bitcoin ATM later attempted to offer. While it was only the next year that the first publicly known bitcoin ATM was installed in Vancouver, maybe it was a misstep from the start after all. Cash is often regarded as a way to deal with traditional finance while reducing your exposure to third-party involvement by banks. There’s something slightly soothing about having a little cash in your sock drawer for emergencies or just the mere ability to know exactly how much money you have on hand. The cash economy is one that seems to be changing but is unlikely to go away quietly. The ability to convert cash to bitcoin or quickly get bitcoin for cash appears to paint the bitcoin ATM positively. Still, the increase in restrictions for using bitcoin ATMs in many countries, as well as significant fees that are often hidden in the price spread on these devices, takes the shine off this benefit quickly upon doing the math. Long Live Peer-to-Peer Trading It’s no surprise people commonly seek to exchange their cash for bitcoin with the often aggressive approach banks have taken towards those that trade cryptocurrency. Over the years, there have been countless complaints from those in the cryptocurrency community across the world of blocked exchange deposits and account closures with murky, at best excuses. While once LocalBitcoins was the best way to solve this problem and have more control over your trades and your financial privacy, the sudden removal of cash trades and increasing restrictions, in my opinion, have stifled this once great tool. While the most well-established P2P exchange may have struggled to evolve in this way. (my recommendation: ). It has taken up the torch and has stepped up to provide P2P trading to not just those suffering from restricted access to documentation, banking, and financial infrastructure in general, but to those of us who just want to trade with a degree of freedom or privacy. LocalCoinSwap The Shiny New Toy Sometimes Becomes an Awkward Memory When bitcoin ATMs first started to appear in metropolitan areas across the world, this was a thing that had many people in the space excited, this sign of adoption brought hope to those already waiting inside the industry. Whether you were involved in a cryptocurrency business, in trading, or are just interested in this technology’s speculative potential, the existence of this device and it’s strange attempt to combine two clashing worlds sparked hope and intrigue among many of us. In practice though, it seems they stumbled long before they ran as the novelty has worn thin, and they became perhaps what they always were, an awkward idea that seemed logical at first glance but merely wasn’t adept at adjusting to the changes in the world around it. While cryptocurrency is seemingly here to stay, the bitcoin ATM may not endure the winds of change in the same way.

Are Bitcoin ATMs An Anomaly or Just an Aberration?

Peer-to-peer trading is a strange phenomenon in some ways, as access to cryptocurrency has grown, so has P2P trading. It’s an odd thing that may not make a lot of sense at first, but when you consider that perhaps those engaging in this form of trading are doing a little more than just, well, trading it gets a bit more intriguing. While cryptocurrency has changed in a lot of ways since the inception of bitcoin, the demand for P2P trading has only increased, and I’d like to explore that interesting dynamic a little with you. My Love-Hate Relationship with Banks While I considered titling this portion “why banks suck and I hate them”, I realised that I don’t, at least not entirely. I can’t argue with the convenience afforded by layering modern payment methods on top of traditional banking. This combination allows me to buy absurd things on eBay I probably don’t need, but buy anyway because I can blast through the checkout with the help of PayPal attached to my bank account like a tick. Convenience matters, and that’s part of the problem with banks. Ever had a transaction bounce back and the bank flag it saying essentially “yeah sorry buddy we’re not going to do that and if you keep trying we’ll probably close your account”, not in the least bit convenient. Furthermore, speaking with a bank about their arbitrary decisions to do or not do something is often fruitless and something anyone that has been involved in cryptocurrency for a while has likely dealt with at one point or another. If you are yet to experience the joy of these encounters, just imagine being a kid again and asking your over-tired parent “why” only to hear back “because I said so”. As someone that works not just in cryptocurrency but at a P2P exchange (my recommendation: ), I’ve not only experienced this kind of thing myself but regularly hear stories of this happening to those in the crypto community around me. LocalCoinSwap The Current State of P2P Trading P2P trading has encountered some significant shakeups recently with the ban on cash trades from one of the largest P2P exchanges, and with some exchanges moving to place seemingly ever-increasing restrictions on traders, it hasn’t been easy for those established on these platforms. However, P2P trading is still booming and doesn’t show any signs of slowing down. There’s a strong userbase not just in countries that lack access to banking or have regulatory restrictions on cryptocurrency, but also countries that have plenty of options for trading crypto. The United States, Australia, and many other countries that have domestic exchanges with significant trading volume still have a very active userbase on P2P exchanges. While all this makes sense and follows the growth of crypto in recent years, it’s also a little peculiar. With so many ways to get in or out of cryptocurrency these days and exchanges with high leverage trading or absurd amounts of trading pairs, why would people still use P2P exchanges? While trading P2P has gotten a little more difficult in some ways, or at least on some platforms, its value proposition hasn’t actually changed. When Trading Crosses Boundaries Trading P2P doesn’t just cross borders; it crosses boundaries. Typically when you think of trading, you likely don’t consider the counterparty in the trade, but perhaps it’s time to look a little harder. When you enter a P2P trade, either as a casual trader or as something you do to earn a living, you are providing a service. You may be providing convenience, allowing someone to buy bitcoin with PayPal or sell unwanted gift cards for ethereum. Even if you are exploiting a bitcoin price premium in a specific region, you are helping indirectly to provide liquidity in that area that helps provide more equilibrium between supply and demand. In some way, what you are essentially doing is not just trading, but providing a service. Whatever the benefit, be it access or convenience there’s something more here you just won’t find on your typical order book exchange, and perhaps that matters in itself. The ability of P2P exchanges to create a link between traders anywhere in the world has arguably not just helped cryptocurrency grow but helped to foster the more stable market we now enjoy. While bitcoin and other cryptocurrencies can still be extremely volatile, the regional arbitrage opportunities only seem to be reducing. With crypto able to cross the planet with minimal friction, the flow of cryptocurrency is more responsive, and this has helped fill a hole the broader community would otherwise likely be struggling with significantly more than we do. Reducing Regulatory Slippage As various regions ebb and flow in regards to their moods on cryptocurrency, this can not just affect the market, but the lives of people all over the world. Having access to cryptocurrency provides the ability for those that need it to help escape hyperinflation or even allow for capital flight from a dangerous situation in an unstable region. If people are restricted to trading on platforms that only allow for heavily monitored and controlled payment methods like wire/bank transfer than a lot of this safety net is gone. Trading P2P keeps trading flexible, it allows you to work with what you have and this is an indispensable part of what makes it great. The service provided by everyone that gets involved with P2P trading helps provide a safety net for those that need it while offering convenience to themselves to be able to trade their own way. The thing I consider more important about having this freedom when trading is it keeps things more reasonable. When things are easily restricted, regulatory overreach can begin to clamp down, leaving many who either need or want access to cryptocurrency left out in the cold. Were it not for the existence of cash we’d likely be experiencing a far different reality when it comes to finances in the modern world (the reason I have a significant distaste for cash restrictions), and I believe this to be the same for cryptocurrency. Conclusionary Ramblings Cryptocurrency has the potential to be a driving force of innovation in the years to come, and my belief is that this long-standing method of trading it will help us on that path forward unencumbered. While P2P trading will evolve with time and the needs of traders shifts a little here and there, the service provided not just between P2P traders themselves, but to the broader cryptocurrency space shouldn’t be ignored. Maybe the next time you are thinking about throwing a little more cash into crypto or selling off some gains, you could consider a little differently. how you are trading

Could Trading-Crypto-as-a-Service Become A Thing?

Caption: Chaintimes History Bitcoin was the discovery of either an individual or a group of people with the pseudonym “ ”. Satoshi wrote the whitepaper (a paper that presents a problem and provides a solution) in 2008 called “ ”. Satoshi Nakamoto Bitcoin: A Peer-to-Peer Electronic Cash System Satoshi’s vision was to build a globally accessible digital currency (cryptocurrency, i.e. cryptographically encrypted currency) that was not backed up by any government. The decentralisation allows this new currency not to be impacted by monetary policies (actions by central banks to manage the money supply), limits any exposure to third parties (such as banks where we hold cash), the payments are immune to inflation/deflation and payments can be borderless i.e. all you need is a mobile device. In summary, your information is safe and cannot be tampered (censorship-resistant), you own and control your assets (self-sovereign) and you can get value from contributions (open ecosystems). Today there are a lot of different cryptocurrencies/coins such as Ethereum, Monero, etc. and each one of them is trying to solve a problem, but the most dominant one is still the Bitcoin (BTC) itself (almost 70% market capitalisation of the crypto market). There is a total maximum of 21 million bitcoins that can ever be mined of which 85%+ has been currently mined as of the . 24.08.2019 A Web of Blocks Similarly to the world wide web (www) and to sending an email, a bitcoin transaction can travel from one peer to another, but this time through blocks i.e. ledger entries. These blocks allow data to be stored and recorded (ledger) and when linked together they form what is called a chain of blocks i.e. a blockchain. Data is encrypted through hash codes which can be defined as cryptographic verification functions with a fixed length whilst their ID is linked with the previous block that can be called or referenced. Caption: Simply Explained Therefore, a user can send a bitcoin or a fraction of a bitcoin to another user by knowing his or her public key. The transaction will then travel through blocks (hash discovery) until it reaches the receiver. All the transactions will be recorded in the series of block transfers, i.e. through the blockchain, which can be defined as a transparent database or a shared public ledger. In this way adjustments can be verified, and the spendable balances can be adjusted for each wallet (receiving addresses), therefore the rightful known owners can know their balances. Caption: Sysjolt The Mechanism Every bitcoin account has the following elements: A 256bits long, to ensure that the owner of this address can receive funds; Public key A or seed used to sign transactions, i.e. a secret piece of data (similar to a password — never to be relieved); Private key Ability to process transactions through a process called . Mining Private keys provide a mathematical proof that they come from the owner of a wallet. Mining uses a consensus mechanism that confirms all pending transactions and allocates them into the blockchain. In this way the transactions are in a chronological order, neutral and allow various computers to agree on the state of the system. The rules prevent previous blocks from being modified and also create a competitive lottery that prevents any individual from easily adding new blocks consecutively to the Blockchain. Mining in Detail To mine bitcoins, you need a software program. This specialised software programme searches for a solution to a difficult math problem. This solution is also referred as or proof-of-work, a solution that is hard to be found but easy to verify. PoW The difficulty of the mathematical problem is automatically adjusted every time a solution is found. The solution is broadcasted, and everyone knows about this newly found solution that exists, and with this new information packaged the result is a new “block” every 10 minutes. The miner is then rewarded with a block compensation, i.e. bitcoin fractions of gets distributed among the peers depending on their hash rate contribution to the process. 12.5BTC The reward can also be impacted due to the level of complexity i.e. in a process called halving, whereas through a programmed bitcoin feature the block reward is cut in half, and it occurs every four years (210,000 blocks) once that number is crossed. Each block contains a block hash that represents the work that has been done by the miner; in other words, this is the proof-of-work. Credit: Binance How to buy your first Bitcoin? In order to purchase your first Bitcoin someone needs to be able to sell you one, or you can decide to mine your own one if you have the right software and computer hardware. Some of the best places to buy Bitcoins: https://localcoinswap.com https://paxful.com https://bisq.network Businesses that accept Bitcoin: https://coinmap.org/welcome https://coinmap.it https://spendabit.co https://99bitcoins.com/bitcoin/who-accept s https://purse.io https://paywithmoon.com https://www.bitrefill.com https://www.egifter.com https://www.gyft.com https://bitcoin.travel Also, a special thanks to https://bitcoin.org for its resources (a bit outdated but still a decent starting point) for educating people about bitcoin.

Understand Bitcoin in just 835 Words

If you've ever needed to get something in order, the first thought that comes to mind is often, "let's sort this out!" And with JavaScript, that sentiment remains true. A great way to quickly rearrange data is by using the Array sort() method. Whether you're a beginner or a pro programmer, it's important to understand how the Array function works in JavaScript. sort() In this guide, we'll give you a detailed overview of what the function does and how it can help you arrange data quickly and easily. sort() We'll cover topics such as sorting of strings, numbers, and objects, as well as discuss the different types of sorting algorithms available and when to use them. arrays So, let's get started on our journey into the world of JavaScript ! sort() Overview of Javascript array Sort() Are you looking for a way to sort your array in Javascript? The Javascript method can be a great tool for organizing your data so that you can quickly and easily make changes to it. sort() This guide will provide you with an overview of the Javascript array sort() method and how it can help you organize your data. Using the sort() method, you can take an array of objects and rearrange them alphabetically, numerically, or according to any custom criteria. To use this method, all you have to do is call the function with two optional arguments - a "compare" function and a "options" object. The options object lets you specify how to sort the array - ascending or descending order, for example - while the compare function lets you define custom sorting logic. Simply put, the Javascript array method is an incredibly powerful tool that makes it easy to organize and manipulate data in almost any way imaginable. sort() With just a few lines of code, you can quickly start sorting arrays with ease. So if you're looking for an efficient way to manage your data, Javascript's method is worth checking out! sort() Best Practices for Sorting Javascript Arrays If you're ready to start sorting your , there are a few best practices to keep in mind. Every situation is unique, and your code will depend on the values you're working with and the outcome you're trying to achieve. Javascript arrays However, here are a few best practices for Javascript array that will help get you started: sort() Make sure to look over your array before sorting it: It's important to double-check everything before initiating the sort(). This way, you can make sure that there are no , invalid data types, or empty strings that could potentially cause the process to fail. duplicate values sort() Understand the different methods of sorting: When it comes to javascript array sort(), there are a number of different methods available for use depending on your needs. Some of the most popular options include , , and . sort() reverse() splice() slice() Consider using a callback function: Callback functions can be incredibly helpful when using a javascript array . These functions allow you to define custom sorting criteria when sorting complex objects or arrays with multiple values. sort() It's important to keep in mind that have performance implications and should be used cautiously. callback functions How to Sort Javascript Arrays With Sort() To use the sort () method, pass a function that defines the pattern for sorting objects in the array. This can be as simple as sorting strings in alphabetical order or as complex as sorting arrays of objects by a certain attribute. For example, if you wanted to sort an array of objects by a user name, you could use: array.sort((a, b) => {
    const nameA = a.userName.toUpperCase();
    const nameB = b.userName.toUpperCase();

    if (nameA < nameB) {
        return -1;
    }

    if (nameA > nameB) {
        return 1;
    }

    return 0;
}); How to Sort Array Numbers With Sort() You can also use the method to sort an array of numbers by ascending or descending order. sort() To sort an array in ascending order, you will need to pass a function as an argument that tells how to compare two elements within the array. sort() A common way to do this is with a custom function that takes two parameters, and , and performs a comparison between them. You can use the or operators to determine what order the elements should be in. a b > (greater than) < (less than) If you want the array sorted in ascending order, you should return a value greater than 0 if , and less than 0 if . a > b a < b How to Sort Numbers With Sort() Here’s an example of how to sort an array of numbers: let numbers = [9, 10, 3, 4];
	numbers.sort(function (a, b) {
	return a - b;
  });

// Example
console.log(numbers); // Logs [3, 4, 9, 10] The code first creates an array called “numbers” with four elements inside, it then uses the sort() method on this array. We pass a custom function as a parameter that takes two parameters “a” and “b” and performs a comparison between them using the less-than operator ( < ) which returns true if “a” is less than “b” otherwise false. The values returned from our custom function determine what order How to Sort an Array of Objects With Sort() To sort an array of objects in JavaScript, you can use the method of the array and pass a comparison function as an argument. sort() The comparison function should take two objects from the array as arguments and return a negative number, 0, or a positive number depending on whether the first object should come before, equal to, or after the second object in the sorted array. const students = [
  { name: 'Alice', grade: 90 },
  { name: 'Bob', grade: 80 },
  { name: 'Charlie', grade: 95 },
  { name: 'David', grade: 85 }
];

students.sort((student1, student2) => student2.grade - student1.grade);

console.log(students);
// Output: [
//   { name: 'Charlie', grade: 95 },
//   { name: 'Alice', grade: 90 },
//   { name: 'David', grade: 85 },
//   { name: 'Bob', grade: 80 }
// ] In this example, we have an array of objects representing students with their names and grades. We want to sort the array in descending order of grade, so we pass a comparison function to that takes two students and subtracts their grades ( ). sort() student2.grade - student1.grade If the result is negative, it means that the first student has a higher grade and should come before the second student in the sorted array. If the result is positive, it means that the second student has a higher grade and should come before the first student. If the result is zero, it means that the students have the same grade, and their order doesn't matter. How to Sort an Array of Strings With Sort() By default, sorts the elements of an array in ascending order based on their . That means that uppercase letters come before lowercase letters, and numbers come before letters. sort() Unicode values However, you can provide a custom sorting function to to define your own sorting technique. sort() const fruits = ['banana', 'apple', 'orange', 'pineapple'];
fruits.sort(); // ['apple', 'banana', 'orange', 'pineapple']

console.log(fruits); In this example, the array is sorted in ascending order based on the default sorting technique. fruits If you want to sort an array of strings in descending order, you can provide a custom sorting function to : sort() const fruits = ['banana', 'apple', 'orange', 'pineapple'];
fruits.sort((a, b) => b.localeCompare(a)); // ['pineapple', 'orange', 'banana', 'apple']

console.log(fruits); In this example, the method is called with a custom sorting function that uses the method to compare two strings. sort() localeCompare() The method returns a negative value if should come before , a positive value if should come after , and if and are equal. localeCompare() a b a b 0 a b By reversing the order of and , we can sort the array in descending order. a b Different Sort Methods in Javascript If you're getting started with javascript array sort(), you can learn about the different sorting methods available. There are different kinds of sorting algorithms, and each one offers something depending on what you're trying to accomplish. Below is a breakdown of the different sorting methods and when you should use each one. Bubble Sort Bubble sort is one of the simplest sorting algorithms available in JavaScript. It's an algorithm that compares two adjacent elements in an array, and then swaps their positions if the order is wrong. This algorithm is good for small datasets, but it's not recommended for large ones because it's very slow. function bubbleSort(arr) {
  var len = arr.length;
  for (var i = 0; i < len - 1; i++) {
    for (var j = 0; j < len - 1 - i; j++) {
      if (arr[j] > arr[j + 1]) {
        var temp = arr[j];
        arr[j] = arr[j + 1];
        arr[j + 1] = temp;
      }
    }
  }
  return arr;
}

// Example 
var myArray = [5, 3, 1, 4, 2];
var sortedArray = bubbleSort(myArray);
console.log(sortedArray); // [1, 2, 3, 4, 5] Insertion Sort Insertion sort orders items by iterating over subarrays until all elements are sorted in the right order. This type of sort is faster than bubble sort and works well with small datasets or already partially-sorted arrays. It's also relatively easy to understand, making it a great option for beginners. function insertionSort(arr) {
  for (let i = 1; i < arr.length; i++) {
    let current = arr[i];
    let j = i - 1;
    while (j >= 0 && arr[j] > current) {
      arr[j + 1] = arr[j];
      j--;
    }
    arr[j + 1] = current;
  }
  return arr;
}

// Example
const arr = [5, 1, 3, 6, 4, 2];
console.log(insertionSort(arr)); // [1, 2, 3, 4, 5, 6] Selection Sort Selection sort works by selecting the smallest element from an unsorted array and putting it at its correct position within the array. It does this by looping through the array, finding the smallest element, and swapping it with its current position until all elements are sorted correctly. This type of sort algorithm can be faster than other methods, especially if there are a lot of duplicate elements in an array. function selectionSort(arr) {
  for (let i = 0; i < arr.length - 1; i++) {
    let minIndex = i;
    for (let j = i + 1; j < arr.length; j++) {
      if (arr[j] < arr[minIndex]) {
        minIndex = j;
      }
    }
    if (minIndex !== i) {
      let temp = arr[i];
      arr[i] = arr[minIndex];
      arr[minIndex] = temp;
    }
  }
  return arr;
}

// Example
const arr = [5, 3, 6, 2, 7];
const sortedArr = selectionSort(arr);
console.log(sortedArr); // [2, 3, 5, 6, 7] Merge Sort Merge sort is a powerful sorting algorithm that can be used to quickly and efficiently sort large datasets. It works by splitting an array into individual subarrays, sorting each of them, and then combining them back together in the correct order. It's a recursive algorithm, meaning that it calls itself multiple times with smaller input each time, so it can be quite slow when dealing with large data. Merge sort is fairly easy to understand and provides a great balance between performance and efficiency. Read more about merge sort -> https://stackabuse.com/merge-sort-in-javascript/ You'll see me writing more on these algorithms and explaining them bit by bit in a very simple way in upcoming blog posts. Conclusion In short, the Javascript method is an incredibly useful way to organize an array, whether you’re sorting numbers, strings, or objects. sort() The sorting process is really easy to implement and understand, but it’s important to have a general understanding of the function so you can get the most out of it. There are a lot of options and customizations to the array sort in JavaScript, so be sure to take full advantage of all it has to offer. So now that you know the basics of arguably the most important method in all of JavaScript, you’re ready to build powerful and efficient websites and apps. Hustle! Read More in JavaScript Polymorphism in JS JavaScript Modules

Sorting an Array in JavaScript: A Beginner's Guide

I’ve spent the last few weeks learning about compose and decided to write a post to share my notes. This post is not meant to teach you everything about Compose but rather it’ll be more like a roadmap that you can use to learn Compose or to see what you still don’t know about Compose. This article will be constantly updated as I learn new things. State hoisting State hoisting is a pattern of moving state up to make a component stateless. When applied to composables, this often means introducing two parameters to the composable. value: T – the current value to display onValueChange: (T) -> Unit – an event that requests the value to change, where T is the proposed new value CompositionLocal Tool for passing data down through the Composition implicitly. CompositionLocalProvider(LocalContentAlpha provides ContentAlpha.medium) {
  Text(...)
}
CompositionLocalProvider(LocalContentAlpha provides ContentAlpha.disabled) {
  Icon(...)
  Text(...)
} compositionLocalOf Changing the value provided during recomposition invalidates only the content that reads its current value. data class Elevations(val card: Dp = 0.dp, val default: Dp = 0.dp)
val LocalElevations = compositionLocalOf { Elevations() } // Create composition with default value

val elevations = Elevations(card = 4.dp, default = 2.dp) // Provide different value here
CompositionLocalProvider(LocalElevations provides elevations) { ... } staticCompositionLocalOf Reads of a are not tracked by Compose. Changing the value causes the entirety of the content lambda where the CompositionLocal is provided to be recomposed. staticCompositionLocalOf If the value provided to the CompositionLocal is highly unlikely to change or will never change, use to get performance benefits. staticCompositionLocalOf Keeping track of changes remember A value computed by remember will be stored in the composition tree, and only be recomputed if the keys to remember change. When adding memory to a composable, always ask yourself “will some caller reasonably want to control this?” If the answer is yes, make a parameter instead. If the answer is no, keep it as a local variable. Remember stores values in the Composition, and will forget them if the composable that called remember is removed. This means you shouldn’t rely upon remember to store important things inside of composables that add and remove children such as . LazyColumn rememberSaveable It behaves similarly to remember, but the stored value will survive the activity or process recreation using the saved instance state mechanism rememberUpdatedState In some situations you might want to capture a value in your effect that, if it changes, you do not want the effect to restart. Create a reference to this value which can be captured and updated. rememberLauncherForActivityResult val result = remember { mutableStateOf<Bitmap?>(null) }
val launcher = rememberLauncherForActivityResult(ActivityResultContracts.TakePicturePreview()) {
  result.value = it
}

Button(onClick = { launcher.launch() }) { ... }

result.value?.let { image ->
  Image(image.asImageBitmap(), null, modifier = Modifier.fillMaxWidth())
} rememberCoroutineScope In order to launch a coroutine outside of a composable, but scoped so that it will be automatically canceled once it leaves the composition is used for scoping jobs initiated by the composition. is for scoping jobs initiated by a user interaction. LaunchedEffect rememberCoroutineScope LaunchedEffect Call suspend functions safely from inside a composable. The coroutine will be cancelled if LaunchedEffect leaves the composition. If LaunchedEffect is recomposed with different keys, the existing coroutine will be cancelled and the new suspend function will be launched in a new coroutine. val currentOnTimeout by rememberUpdatedState(onTimeout)

LaunchedEffect(true) {
  delay(SplashWaitTimeMillis)
  currentOnTimeout()
} snapshotFlow Convert Compose State<T> objects into a Flow. DisposableEffect DisposableEffect is meant for side effects that need to be cleaned up after the keys change or the composable leaves the Composition. DisposableEffect(dispatcher) {
  dispatcher.addCallback(backCallback)
  onDispose {
    backCallback.remove()
  }
} derivedStateOf derivedStateOf is used when you want a Compose State that’s derived from another State. State Holder State holders always need to be in order to keep them in the Composition and not create a new one every time. It’s a good practice to create a method in the same file that does this to remove boilerplate and avoid any mistakes that might occur. remembered Layouts LazyColumn and LazyRow Don’t recycle their children like RecyclerView. It emits new Composables as you scroll through it and is still performant as emitting Composables is relatively cheap compared to instantiating Android Views. val listState = rememberLazyListState()

LazyColumn(
  contentPadding,
  verticalArrangement / horizontalArrangement = Arrangement.spacedBy
) {
  stickyHeader { Header()  } // Experimental
  items(5) { index -> Text(text = "Item: $index") } // key = ...
  item { Text(text = "Last item") }
}

LaunchedEffect(listState) {
  snapshotFlow { listState.firstVisibleItemIndex }
}

firstVisibleItemIndex
firstVisibleItemScrollOffset

scrollToItem()
animateScrollToItem() ConstraintLayout ConstraintLayout {
  val (button, text) = createRefs()

  Button(
    modifier = Modifier.constrainAs(button) {
      top.linkTo(parent.top, margin = 16.dp)
    }
  )

  Text("Text", Modifier.constrainAs(text) {
    top.linkTo(button.bottom, margin = 16.dp)
  })
}

ConstraintSet {
  val button = createRefFor("button")
  val text = createRefFor("text")

  constrain(button) { ... }
  constrain(text) { ... }
} Layout Instead of controlling how a single composable gets measured and laid out on the screen, you might have the same necessity for a group of composables. For that, you can use the Layout composable to manually control how to measure and position the layout’s children. Layout(
  modifier = modifier,
  content = content
) { measurables, constraints ->
  // Don't constrain child views further, measure them with given constraints
  val placeables = measurables.map { measurable -> measurable.measure(constraints) }

  // Set the size of the layout as big as it can
  layout(constraints.maxWidth, constraints.maxHeight) {
    var yPosition = 0

    placeables.forEach { placeable ->
      placeable.placeRelative(x = 0, y = yPosition)
      yPosition += placeable.height
    }
  }
} Intrinsic measurements Row(modifier = modifier.height(IntrinsicSize.Min)) Navigation val navController = rememberNavController()
val backstackEntry = navController.currentBackStackEntryAsState()

NavHost(navController = navController, startDestination = "profile") {
  composable(
    "profile/{userId}/?mode={mode}",
    arguments = listOf(
      navArgument("userId") { type = NavType.StringType },
      navArgument("mode") { defaultValue = "lite" },
    ),
    deepLinks = listOf(navDeepLink {
      uriPattern = "rally://$accountsName/{name}"
    })
  ) { 
    Profile(/*...*/) 
  }
  
  loginGraph()
}

fun NavGraphBuilder.loginGraph(navController: NavController) {
  navigation(startDestination = "username", route = "login") {
    composable("username") { ... }
  }
}

navController.navigate("friends") {
  popUpTo("home") { inclusive = true }
}

navController.navigate(screen.route) {
  // Pop up to the start destination of the graph to avoid building up a large stack 
  // of destinations on the back stack as users select items
  popUpTo(navController.graph.findStartDestination().id) {
    saveState = true
  }
  // Avoid multiple copies of the same destination when reselecting the same item
  launchSingleTop = true
  // Restore state when reselecting a previously selected item
  restoreState = true
} ViewModel @HiltViewModel
class ExampleViewModel @Inject constructor(
  ...
) : ViewModel() { /* ... */ }

@AndroidEntryPoint
class ExampleActivity : AppCompatActivity()

@Composable
fun ExampleScreen(
  exampleViewModel: ExampleViewModel = viewModel()
) { /* ... */ } Animation You can create an animation value by simply wrapping the changing value with the corresponding variant of composables. animate*AsState Float, Color, Dp, Size, Bounds, Offset, Rect, Int, IntOffset, and IntSize You can combine multiple transition objects with a + operator. MutableTransitionState(false).apply {
  targetState = true  // Start the animation immediately
  // isIdle, currentState
} AnimatedVisibility Content within (direct or indirect children) can use the animateEnterExit modifier to specify different animation behavior for each of them. AnimatedVisibility AnimatedContent defines how the size should animate between the initial and the target contents. SizeTransform animateContentSize Animates a size change Crossfade Animates between two layouts with a crossfade animation. Animatable Animatable is a value holder that can animate the value as it is changed via . animateTo sets the current value to the target value immediately. snapTo starts an animation that slows down from the given velocity. animateDecay val color = remember { Animatable(Color.Gray) }
LaunchedEffect(ok) { color.animateTo(if (ok) Color.Green else Color.Red) }InfiniteTransition InfiniteTransition Holds one or more child animations like Transition, but the animations start running as soon as they enter the composition and do not stop unless they are removed. Use the function. rememberInfiniteTransition Transition Transition manages one or more animations as its children and runs them simultaneously . between multiple states var currentState by remember { mutableStateOf(BoxState.Collapsed) }
val transition = updateTransition(currentState)

// Start in collapsed state and immediately animate to expanded
var currentState = remember { MutableTransitionState(BoxState.Collapsed) }
currentState.targetState = BoxState.Expanded
val transition = updateTransition(currentState)

transition.AnimatedVisibility
transition.AnimatedContent AnimationSpec spring(
  dampingRatio = Spring.DampingRatioHighBouncy,
  stiffness = Spring.StiffnessMedium
)

tween(
  durationMillis = 300,
  delayMillis = 50,
  easing = LinearOutSlowInEasing
)

// animates based on the snapshot values specified at different timestamps
keyframes {
  durationMillis = 375
  0.0f at 0 with LinearOutSlowInEasing // for 0-15 ms
  0.2f at 15 with FastOutLinearInEasing // for 15-75 ms
  0.4f at 75 // ms
  0.4f at 225 // ms
}

// runs a animation repeatedly until it reaches the specified iteration count
repeatable(
  iterations = 3,
  animation = tween(durationMillis = 300),
  repeatMode = RepeatMode.Reverse
)

// like repeatable, but it repeats for an infinite amount of iterations
infiniteRepeatable(
  animation = tween(durationMillis = 300),
  repeatMode = RepeatMode.Reverse
)

// immediately switches the value to the end value
snap(delayMillis = 50) Theming When defining colors, we name them “literally”, based on the color value, rather than “semantically” e.g. Red500 not primary. This enables us to define multiple themes e.g. another color might be considered primary in dark theme or on a differently styled screen. isSystemInDarkTheme() / MaterialTheme.colors.isLight color: Color = MaterialTheme.colors.surface, contentColor: Color = contentColorFor(color) When setting the color of any elements, prefer using a Surface to do this as it sets an appropriate content color value, be wary of direct Modifier.background calls which do not set an appropriate content color. CompositionLocal TextFieldDefaults textFieldColors outlinedTextFieldColors ProvideTextStyle So how do components set a theme typography style? Under the hood they use the composable (which itself uses a CompositionLocal) to set a “current” TextStyle. The Text composable defaults to querying this “current” style if you do not provide a concrete textStyle parameter. ProvideTextStyle Resources stringResource(R.string.congratulate, "New Year", 2021)
dimensionResource(R.dimen.padding_small)

painterResource(id = R.drawable.ic_logo)
animatedVectorResource(id = R.drawable.animated_vector)

Icon(Icons.Rounded.Menu) Fonts private val light = Font(R.font.raleway_light, FontWeight.W300)
private val regular = Font(R.font.raleway_regular, FontWeight.W400)
private val medium = Font(R.font.raleway_medium, FontWeight.W500)
private val semibold = Font(R.font.raleway_semibold, FontWeight.W600)

// Create a font family to use in TextStyles
private val craneFontFamily = FontFamily(light, regular, medium, semibold) buildAnnotatedString buildAnnotatedString {
  append("This is some unstyled text\\n")
  withStyle(SpanStyle(color = Color.Red)) {
    append("Red text\\n")
  }
  pushStringAnnotation(tag = "URL", annotation = "<https://developer.android.com>")
  withStyle(SpanStyle(fontSize = 24.sp)) {
    append("Large text")
  }
  pop()
} Generic Modifiers align
alignBy

// animateEnterExit modifier can be used for any direct or indirect children 
// of AnimatedVisibility to create a different enter/exit animation than 
// what's specified in AnimatedVisibility.
animateEnterExit(enter, exit)

border
background
clip
clipToBounds

drawBehind
drawWithCache
drawWithContent

// The draw layer can be invalidated separately from parents. 
// scaleX, scaleY, rotationXYZ, alpha, shadowElevation, shape, clip, shape
// Use with state values such as ScrollState or LazyListState
graphicsLayer

shadow
zIndex

onKeyEvent

// Creates a LayoutModifier that allows changing how the wrapped element is 
// measured and laid out.
layout

absoluteOffset
offset

fillMaxHeight, fillMaxWidth, fillMaxSize
// matches the size of the Box after all other children have been measured 
// to obtain the Box's size.
matchParentSize

heighIn(min, max), widthIn(min, max) Gesture Modifiers combinedClickable(onLongClick, onDoubleClick, onClick)

draggable(
  orientation = Orientation.Horizontal,
  state = rememberDraggableState { delta ->
    val newValue = offsetPosition.value + delta
    offsetPosition.value = newValue.coerceIn(minPx, maxPx)
  }
)

swipeable(
  state = swipeableState,
  anchors = anchors,
  thresholds = { _, _ -> FractionalThreshold(0.3f) },
  orientation = Orientation.Horizontal
)

pointerInput(Unit) {
  detectTapGestures(onPress, onDoubleTap, onLongPress, onTap)
  detectDragGestures { change, dragAmount ->
    change.consumeAllChanges()
    offsetX += dragAmount.x
    offsetY += dragAmount.y
  }
}

horizontalScroll, verticalScroll

// Detects the scroll gestures, but does not offset its contents.
// Has nested scroll built in
scrollable

nestedScroll(nestedScrollConnection, nestedScrollDispatcher) Miscelaneous LocalSoftwareKeyboardController val keyboardController = LocalSoftwareKeyboardController.current
// Calling this function is considered a side-effect and should not be called directly from recomposition
keyboardController.hide() LocalOnBackPressedDispatcherOwner and BackHandler var backHandlingEnabled by remember { mutableStateOf(true) }
var backPressedCount by remember { mutableStateOf(0) }
BackHandler(backHandlingEnabled) { backPressedCount++ }

val dispatcher = LocalOnBackPressedDispatcherOwner.current!!.onBackPressedDispatcher

Button(onClick = { dispatcher.onBackPressed() }) {
  Text("Press Back count $backPressedCount")
} LocalDensity val sizeInPx = with(LocalDensity.current) { 16.dp.toPx() }
val (minPx, maxPx) = with(LocalDensity.current) { min.toPx() to max.toPx() } FocusRequester val focusRequester = remember { FocusRequester() }
var color by remember { mutableStateOf(Black) }
Box(
  Modifier
    .clickable { focusRequester.requestFocus() }
    .border(2.dp, color)
    // The focusRequester should be added BEFORE the focusable.
    .focusRequester(focusRequester)
    // The onFocusChanged should be added BEFORE the focusable that is being observed.
    .onFocusChanged { color = if (it.isFocused) Green else Black }
    .focusable()
) Thank you for reading. If you have any suggestions feel free to contact me. Resources https://developer.android.com/jetpack/compose/architecture https://developer.android.com/jetpack/compose/resources https://developer.android.com/jetpack/compose/animation https://developer.android.com/jetpack/compose/gestures https://developer.android.com/jetpack/compose/navigation https://developer.android.com/jetpack/compose/modifiers-list https://developer.android.com/jetpack/compose/mental-model https://developer.android.com/jetpack/compose/compositionlocal https://developer.android.com/codelabs/jetpack-compose-basics https://developer.android.com/codelabs/jetpack-compose-layouts https://developer.android.com/codelabs/jetpack-compose-state https://developer.android.com/codelabs/jetpack-compose-theming https://developer.android.com/codelabs/jetpack-compose-animation https://developer.android.com/codelabs/jetpack-compose-navigation https://developer.android.com/codelabs/jetpack-compose-advanced-state-side-effects https://developer.android.com/reference/kotlin/androidx/compose/runtime/saveable/package-summary Also published . here

The Ultimate Jetpack Compose Cheat Sheet

JavaScript arrays are data types that can store a collection of elements. These elements can be of any data type, including numbers, strings, and objects. Arrays in JavaScript are dynamic, meaning that you can add or remove elements from them after they have been created. What are Arrays in JavaScript? In this tutorial, we will look into all the JavaScript array methods and how they are applied in practice. Types of Array methods There are several methods for manipulating JavaScript arrays. Some of these methods are: 1. concat() This method is used to merge two or more arrays. It does not modify the original arrays, but instead returns a new array that contains the elements of the original arrays. Here is an example of how `concat()` can be used in JavaScript: const array1 = [1, 2, 3];
const array2 = [4, 5, 6];
const array3 = [7, 8, 9];

const mergedArray = array1.concat(array2, array3);
// mergedArray is [1, 2, 3, 4, 5, 6, 7, 8, 9] In the example above, array1, array2, and array3 are all merged into a single array called `mergedArray`. `concat()` takes any number of arrays as arguments and returns a new array that contains all the elements of the original arrays. You can also use `concat()` to merge arrays with non-array values. For example: const array1 = [1, 2, 3];
const mergedArray = array1.concat(4, 5, 6);
// mergedArray is [1, 2, 3, 4, 5, 6] In this case, the values 4, 5, and 6 are added to the end of array1 to create the `mergedArray`. Note that `concat()` does not modify the original arrays. Instead, it creates a new array that contains the elements of the original arrays. If you want to modify an array in place, you can use the `push()` method instead. 2.  join() This method is used to join all the elements of an array into a string. It takes an optional separator parameter, which specifies the character to be used to separate the elements of the array in the resulting string. If no separator is provided, the elements are separated by a comma. Here is an example of how `join()` can be used in JavaScript: const array = ['apple', 'banana', 'orange'];
const fruitString = array.join();
// fruitString is 'apple,banana,orange'

const array = [1, 2, 3];
const numberString = array.join('-');
// numberString is '1-2-3' In the first example, the elements of the array are joined into a single string with a comma as the separator. In the second example, the elements of the array are joined into a single string with a hyphen as the separator. You can also use `join()` on an array of arrays to create a string of nested arrays: const array = [[1, 2], [3, 4], [5, 6]];
const nestedArrayString = array.join('-');
// nestedArrayString is '1,2-3,4-5,6' Note that `join()` does not modify the original array. It creates a new string that contains the elements of the array. If you want to modify the array in place, you can use the `splice()` method instead. 3.  pop() This method is used to remove the last element of an array and return it. It modifies the original array. Here is an example of how `pop()` can be used in JavaScript: const array = [1, 2, 3, 4, 5];
const lastElement = array.pop();
// lastElement is 5
// array is [1, 2, 3, 4] In this example, the `pop()` method removes the last element (5) from the array and assigns it to the `lastElement` variable. The array is then modified to remove the last element, leaving it with a length of 4. You can also use `pop()` in combination with other array methods, such as `push()` to add elements to the end of the array: const array = [1, 2, 3];
array.push(4);
array.pop();
// array is [1, 2, 3] In this example, the `push()` method adds the element 4 to the end of the array, and then the `pop()` method removes it again, leaving the array unchanged. Note that if the array is empty, `pop()` returns undefined. const array = []; 
const element = array.pop(); 
// element is undefined 4.  push() This method is used to add one or more elements to the end of an array. It modifies the original array and returns the new length of the array. Here is an example of how push() can be used in JavaScript: const array = [1, 2, 3];
const newLength = array.push(4, 5, 6);
// array is [1, 2, 3, 4, 5, 6]
// newLength is 6 In this example, the push() method adds the elements 4, 5, and 6 to the end of the array and returns the new length of the array (6). The array is then modified to include these elements. You can also use push() to add an array of elements to the end of another array: const array = [1, 2, 3];
const newLength = array.push([4, 5, 6]);
// array is [1, 2, 3, [4, 5, 6]]
// newLength is 4 In this example, the push() method adds the array [4, 5, 6] as a single element to the end of the array, and returns the new length of the array (4). Note that push() modifies the original array. If you want to create a new array that includes the elements of the original array, you can use the concat() method instead. 5. shift() This method is used to remove the first element of an array and return it. It modifies the original array. Here is an example of how shift() can be used in JavaScript: const array = [1, 2, 3, 4, 5];
const firstElement = array.shift();
// firstElement is 1
// array is [2, 3, 4, 5] In this example, the shift() method removes the first element (1) from the array and assigns it to the firstElement variable. The array is then modified to remove the first element, leaving it with a length of 4. You can also use shift() in combination with other array methods, such as unshift() to add elements to the beginning of the array: const array = [1, 2, 3];
array.unshift(0);
array.shift();
// array is [1, 2, 3] In this example, the unshift() method adds the element 0 to the beginning of the array, and then the shift() method removes it again, leaving the array unchanged. Note that if the array is empty, shift() returns undefined. const array = []; 

const element = array.shift(); 

// element is undefined 6. unshift() This method is used to add one or more elements to the beginning of an array. It modifies the original array and returns the new length of the array. Here is an example of how unshift() can be used in JavaScript: const array = [1, 2, 3];
const newLength = array.unshift(4, 5, 6);
// array is [4, 5, 6, 1, 2, 3]
// newLength is 6 In this example, the unshift() method adds the elements 4, 5, and 6 to the beginning of the array and returns the new length of the array (6). The array is then modified to include these elements at the beginning. You can also use unshift() to add an array of elements to the beginning of another array: const array = [1, 2, 3];
const newLength = array.unshift([4, 5, 6]);
// array is [[4, 5, 6], 1, 2, 3]
// newLength is 4 In this example, the unshift() method adds the array [4, 5, 6] as a single element to the beginning of the array, and returns the new length of the array (4). Note that unshift() modifies the original array. If you want to create a new array that includes the elements of the original array, you can use the concat() method instead. 7. slice() This method is used to extract a section of an array and return a new array. It does not modify the original array. The slice method takes two optional parameters: a start index and an end index. If the start index is not specified, it defaults to the start of the array. If the end index is not specified, it defaults to the end of the array. Here is an example of how slice() can be used in JavaScript: const array = [1, 2, 3, 4, 5];
const slice = array.slice(1, 3);
// slice is [2, 3]
// array is [1, 2, 3, 4, 5] (unchanged) In this example, the slice() method extracts the elements at indices 1 and 2 (2 and 3) from the array and returns them in a new array called slice. The original array is not modified. You can also use slice() with a single argument, which indicates the start index: const array = [1, 2, 3, 4, 5];
const slice = array.slice(2);
// slice is [3, 4, 5]
// array is [1, 2, 3, 4, 5] (unchanged) In this case, the slice() method extracts all the elements of the array starting from the index 2 (inclusive) to the end of the array. You can also use negative indices with slice(), which indicates the position of the element relative to the end of the array: const array = [1, 2, 3, 4, 5];
const slice = array.slice(-2);
// slice is [4, 5]
// array is [1, 2, 3, 4, 5] (unchanged) In this case, the slice() method extracts the last two elements of the array. Note that if the start index is greater than the end index, slice() returns an empty array. 8. splice() The splice() method in JavaScript is used to add or remove elements from an array and return the removed elements as a new array. It modifies the original array. The splice() method takes at least two arguments: a start index and a delete count. The start index is the index at which the splice begins, and the delete count is the number of elements to be removed. Here is an example of how splice() can be used to remove elements from an array: const array = [1, 2, 3, 4, 5];
const removedElements = array.splice(1, 2);
// removedElements is [2, 3]
// array is [1, 4, 5] In this example, the splice() method removes the elements at indices 1 and 2 (2 and 3) from the array and returns them in a new array called removedElements. The original array is modified to remove these elements. You can also use splice() to add elements to an array: const array = [1, 2, 3];
const removedElements = array.splice(1, 0, 4, 5, 6);
// removedElements is []
// array is [1, 4, 5, 6, 2, 3] In this case, the splice() method adds the elements 4, 5, and 6 to the array at the index 1, and the delete count is 0, so no elements are removed. The original array is modified to include these elements. You can also use splice() to both add and remove elements at the same time: const array = [1, 2, 3, 4, 5];
const removedElements = array.splice(1, 2, 6, 7);
// removedElements is [2, 3]
// array is [1, 6, 7, 4, 5] In this example, the splice() method removes the elements at indices 1 and 2 (2 and 3) from the array and adds the elements 6 and 7 at the same indices. The original array is modified to include the added elements and remove the removed elements. Note that if the start index is greater than the length of the array, splice() does not add or remove any elements, but simply returns an empty array. 9. reverse() This method is used to reverse the order of the elements in an array. It modifies the original array. Here is an example of how reverse() can be used in JavaScript: const array = [1, 2, 3, 4, 5];
array.reverse();
// array is [5, 4, 3, 2, 1] In this example, the reverse() method reverses the order of the elements in the array, so that the first element becomes the last and the last element becomes the first. You can also use reverse() on an array of objects: const array = [{id: 1}, {id: 2}, {id: 3}];
array.reverse(); // array is [{id: 3}, {id: 2}, {id: 1}] In this case, the reverse() method reverses the order of the objects in the array. Note that reverse() modifies the original array. If you want to create a new array that is the reverse of the original array, you can use the slice() and reverse() methods together: const array = [1, 2, 3, 4, 5];
const reversedArray = array.slice().reverse();
// reversedArray is [5, 4, 3, 2, 1]
// array is [1, 2, 3, 4, 5] (unchanged) In this example, the slice() method creates a shallow copy of the array, and the reverse() method reverses the elements in the copy, leaving the original array unchanged. 10. sort() This method is used to sort the elements of an array in place. It can take an optional compare function as a parameter, which allows you to specify a custom sorting algorithm. If no compare function is provided, the elements are sorted in ascending order according to their Unicode code points. Here is an example of how sort() can be used in JavaScript: const array = [5, 2, 4, 1, 3];
array.sort();
// array is [1, 2, 3, 4, 5] In this example, the sort() method sorts the elements of the array in ascending order. You can also use sort() with a compare function as its argument to specify a custom sort order: const array = [{name: 'John'}, {name: 'Jane'}, {name: 'Bob'}];
array.sort((a, b) => a.name.localeCompare(b.name));
// array is [{name: 'Bob'}, {name: 'Jane'}, {name: 'John'}] In this case, the sort() method sorts the objects in the array based on their name properties using the localeCompare() method. Note that sort() modifies the original array. Also by default, sort() converts the elements of the array to strings and sorts them based on their Unicode point values. This can lead to unexpected results for non-string values. For example: const array = [10, 5, 8, 1, 7];
array.sort();
// array is [1, 10, 5, 7, 8] In this case, the sort() method converts the numbers to strings before sorting them, so the resulting array is not in numerical order. To sort the array in numerical order, you can use a compare function as the argument to sort(): const array = [10, 5, 8, 1, 7];
array.sort((a, b) => a - b);
// array is [1, 5, 7, 8, 10] If you want to sort the elements of an array in descending order, you can use the following compare function as the argument to sort(): const array = [5, 2, 4, 1, 3];
array.sort((a, b) => b - a);
// array is [5, 4, 3, 2, 1] Conclusion These are just a few of the many methods available for working with arrays in JavaScript. I hope this helps! Let me know if you have any other questions.

Array Manipulation: Understanding JavaScript Array Methods

Manipulación de matrices: comprensión de los métodos de matriz de JavaScript

Manipulation de tableau : comprendre les méthodes de tableau JavaScript

ऐरे मैनीपुलेशन: जावास्क्रिप्ट ऐरे मेथड्स को समझना

配列操作: JavaScript 配列メソッドを理解する

Manipulação de Array: Entendendo os Métodos de Array em JavaScript

Thao tác mảng: Hiểu các phương thức mảng JavaScript

数组操作：理解 JavaScript 数组方法

If you are working with JavaScript, you probably use Arrays a lot. Very often, you need to do some kind of manipulation with arrays or iterate through them. In this post, I compiled a list of the most useful array methods that can save you time, and your code will look cleaner and more readable. 1. ForEach This one is the most popular method. Instead of doing or loops to iterate through all elements of an array, we can call the method. The method accepts function as a parameter and calls this function once for each element in the array, in order. for while forEach() forEach() JavaScript var languages = ["C#", "Java", "C++", "PHP", "JavaScript"];

languages.forEach((language, index) => {
   console.log(index+1 + ". " + language);
});

// 1. C#
// 2. Java
// 3. C++
// 4. PHP
// 5. JavaScript method has the following syntax: forEach() array.forEach((currentValue, index, arr) => {
 //do your stuff here
}); – the value of the current element currentValue the array index of the current element index – – the array itself arr The last two parameters (index and arr) are optional. 2. Map The method creates a new array by mapping each value of the original array through a transformation function. The method does not change the original array. map() map() For example, we have an array of numbers and we would like to square all elements of the array. For this purpose we can use the method: map() var numbers = [1,2,3,4];

var squaredNumbers = numbers.map((number) => {
  return number * number;
});

console.log(squaredNumber) // => [1,4,9,16] One more example. We want to create a new array by transforming items of the original array into objects with properties id, name, and category: languages = ["C#", "PHP", "JavaScript"];
const mappedLanguageList = languages.map(function(language, ,index) {
  return {
    id: index + 1,
    name: language,
    category: "Programming Language"
  }; 
}); Map method creates a new array that we store in the mappedLanguageList variable; it does not update the original array. console.log(mappedLanguageList);
// => [
//     {id: 1, name: "C#", category: "Programming Language"},
//     {id: 2, name: "PHP", category: "Programming Language"},
//     {id: 3, name: "JavaScript", category: "Programming Language"}
//    ]
 
console.log(languages);
// => ["C#", "PHP", "JavaScript"] method has the following syntax: map() array.map(function(currentValue, index, arr) {
    //do your mapping here
}); – the value of the current element currentValue the array index of the current element index – – the array itself arr The last two parameters (index and arr) are optional. 3. Find If you would like to find an item in an array that matches a specific condition, you could use the method. The method looks through each element of the array and returns the first one that passes the test, which is provided as a function. The function returns (pass) or (does not pass). And the method returns the value of the element that passes the test. find() find() true false find() Let’s take a look at the following example. Here we have an array of numbers and we would like to find the first even number in the array. [5, 7, 4, 3, 6].find(function(number) {
    return number % 2 === 0;
}); // => 4 In this example, the method returns 4 because it is the first element that passes the test (the function returns true). In the array, the number 6 also passes the test, but the method returns only the first value found and does not check the remaining values. find() find() If no element passes the test, the method returns find() undefined. method has the following syntax: find() array.find(function(currentValue, index, arr) {
    //put your test here
}); – the value of the current element currentValue the array index of the current element index – – the array itself arr The last two parameters (index and arr) are optional. The method does not change the original array. find() 4. Filter The method works similarly to the method but returns a new array filled with all values that pass a test. filter() find() Let’s take the array of numbers from the previous example and find all even numbers in it. [5, 7, 4, 3, 6].filter(function(number) {
    return number % 2 === 0;
});  // => [4, 6] The method created a new array that we store in the variable. filter() evenNumbers If no element passes the test, the method returns an empty array_._ filter() The method has the following syntax: filter() array.filter(function(currentValue, index, arr) {
  //put your test here
}); – the value of the current element currentValue the array index of the current element index – – the array itself arr The last two parameters (index and arr) are optional. The method does not change the original array. filter() 5. Every The method checks if all the elements in the array pass a test that is provided as a function. It returns a boolean value. If it finds at least one element where the function returns false, the method returns false. every() every() [5, 7, 4, 3, 6].every(function(number) {
    return number % 2 === 0;
});
// returns false [4, 8, 6].every(function(number) {
    return number % 2 === 0;
});
//returns true The method has the following syntax: every() array.every(function(currentValue, index, arr) {
  //put your test here
}); – the value of the current element currentValue the array index of the current element index – – the array itself arr The last two parameters (index and arr) are optional. The method does not change the original array. every() 6. Some The method checks if any of the elements in an array pass a test that is provided as a function. It returns a boolean value.  If it finds at least one element where the function returns true the method returns . some() some() true [5, 7, 4, 3, 6].some(function(number) {
    return number % 2 === 0;
});
// returns true The method has the following syntax: some() array.some(function(currentValue, index, arr) {
    //put your test here
}); – the value of the current element currentValue the array index of the current element index – – the array itself arr The last two parameters (index and arr) are optional. The () method does not change the original array. some 7. Sort The method sorts the elements of an array. By default, the method sorts the values as strings in alphabetical and ascending order. This works perfectly for but it does not work for numeric values. sort() sort() strings ["Java", "PHP", "C#", "JavaScript", "Ruby"].sort();
// => ["C#", "Java", "JavaScript", "PHP", "Ruby"]
 
 
[12, 4, 1, 7, 3, 100].sort();
// => [1, 100, 12, 3, 4, 7] As you see, the default behavior is not the best choice for sorting an array by a numeric value. In this case, you need to provide a “compare function”. Ascending order: [12, 4, 1, 7, 3, 100].sort(function(a, b){
    return a-b
});
// => [1, 3, 4, 7, 12, 100] Descending order: [12, 4, 1, 7, 3, 100].sort(function(a, b){
    return b-a
});
// => [100, 12, 7, 4, 3, 1] Sorting array of objects: var people = [
     {name: "Bill", age: 42},
     {name: "Peter", age: 35},
     {name: "Marry", age: 27}
];
 
people.sort(function(a, b) {return a.age - b.age});
// => [{name: "Marry", age: 27}, {name: "Peter", age: 35}, {name: "Bill", age: 42}]; If you would like to sort objects by string value you can use something like this: people.sort(function (a,b) {
   if (a.name < b.name){
     return -1;
   } 
   if (a.name > b.name) {
     return 1;
   }
   return 0;
});
// => [{name: "Bill", age: 42}, {name: "Marry", age: 27}, {name: "Peter", age: 35}] Or simply use string method that does the comparison for you: localeCompare() people.sort(function (a,b) {
   return a.name.localeCompare(b.name)
});
// => [{name: "Bill", age: 42}, {name: "Marry", age: 27}, {name: "Peter", age: 35}] The method has the following syntax: sort() array.sort(compareFunction); – a function that defines an alternative sort order. The function should return a negative, zero, or positive value. This parameter is optional. compareFunction The method changes the original array. sort() Conclusion We looked at useful array methods that make code easier to read and debug. All the operations we looked at can be done with the classic But for and while loops luck is not selfdescribin for or while loops.

The 7 Most Useful Array Methods in JavaScript

Shimmering is present in almost all applications that have networking. When the task of making it on came up, given that the latter simplifies the work with the , I did not find a solution. All options were reduced to downloading fairly heavy libraries or writing a lot of code. However, I managed to find a solution, which allows me to make a shimmering on in a few lines of code. compose view compose Observations and Assumptions my solution won't cover 100% of the cases of shimmering, but it's easy to refine; my solution will be built around the method. There are probably more options, but this one seemed the easiest to me; Brush.linearGradient() Don't forget to include compose if it's a new project, like and others. The full algorithm for adding to a project can be found here: . buildFeatures {compose true}, composeOptions compose https://developer.android.com/jetpack/compose/setup Description I am first attaching the full code of the . You can copy it into your project and run it: ShimmeringActivity https://gist.github.com/45ccb35b9ae80fbddcd2ffc2c0678c44 As a result, you should have the following animation: Don't be intimidated by the orange and blue shimmering colors. I did this on purpose so that they would be easily distinguishable. The color can be changed to white, as it should be in your project. Let's go through the code. Let's start with an easy one: ShimmeringCompose(
   modifier = Modifier
       .width(300.dp)
       .height(150.dp),
   cornerRadius = 16.dp
) - the width, height and radius of the circle, as in any other compose view. width, height, cornerRadius val screenWidth = LocalConfiguration.current.screenWidthDp.dp - the found screen width. This is necessary to make the animation for all elements work synchronously. Otherwise, if there are several rectangles with different widths on the same screen, the shimmering for them will be out of sync, because the animation will run different distances at the same time. screenWidth val translateAnim by rememberInfiniteTransition().animateFloat(
   initialValue = 0f,
   targetValue = screenWidth.px,
   animationSpec = infiniteRepeatable(
       animation = tween(durationMillis = 1500, easing = FastOutSlowInEasing)
   )
) - methods for creating infinite animation. rememberInfiniteTransition().animateFloat(), infiniteRepeatable() - start and end value of the animation. initialValue, targetValue - method for configuring the animation. tween() - animation time. durationMillis - interpolation of the animation. easing The value of will change over time from to . The change logs: translateAnim initialValue targetValue translateAnim D: ShimmeringCompose: 1.2176096
D: ShimmeringCompose: 2.7215502
D: ShimmeringCompose: 7.4594655
D: ShimmeringCompose: 11.377052
D: ShimmeringCompose: 21.533459
D: ShimmeringCompose: 27.730642
D: ShimmeringCompose: 34.646053
D: ShimmeringCompose: 53.458187
D: ShimmeringCompose: 64.20549
D: ShimmeringCompose: 91.909676
D: ShimmeringCompose: 107.303856 val shimmerColorShades = listOf(Color(0xFFF37F19), Color(0xFF007CFF), Color(0xFFF37F19)) With this list the colors are set: blue in the center and orange on the edges. val brush = Brush.linearGradient(
   colors = shimmerColorShades,
   start = Offset(translateAnim, translateAnim),
   end = Offset(translateAnim + 70.dp.px, translateAnim + 35.dp.px)
) is a method for creating a gradient. Brush.linearGradient() In we assign the sheet of colors created above. colors is a shell class for assigning x and y coordinates Offset() The values 70 and 35 are chosen depending on the shimmering design in Figma. Box(modifier = modifier.background(brush = brush, shape = RoundedCornerShape(cornerRadius))) Create a object and assign to it in the values of and to create rounded corners. Box background() brush RoundedCornerShape You will also need a utility method to translate to : dp px val Dp.px: Float
    @Composable
    get() = with(LocalDensity.current) { this@px.toPx() } As a result, we get animation, as in the gif-picture at the beginning of the article. A few words about Brush.linearGradient() To understand how works, change the code in the to the following: Brush.linearGradient() ShimmeringActivity val brush = Brush.linearGradient(
   colors = shimmerColorShades,
   start = Offset(0f, 0f),
   end = Offset(0f, 100f)
) You will end up with the following picture: If you set , the shimmer bar will be parallel to the . The thickness will be , in this case 100f. Now insert the following code: x_start = x_end x-axis y_end - y_start val brush = Brush.linearGradient(
   colors = shimmerColorShades,
   start = Offset(0f, 0f),
   end = Offset(100f, 0f)
) You will get this picture: If you set the coordinates, the shimmer bar will be parallel to the . The thickness will be , in this case 100f. y_start = y_end y-axis x_end - x_start Thus, by manipulating the start and end coordinates, you can achieve the desired result. Conclusion As you can see, creating shimmering took about 25 lines of code, not including the code and the utility method for translating to . From my point of view, pulling in an additional library to create the shimmering makes no sense. Yes, my example isn't exactly clean from a code point of view: some variables aren't moved here and critical situations aren't handled. But it can be easily modified to the needs of your project. ShimmeringActivity px

Design Your Own Shimmering UI in 25 Lines of Code with Compose

Sorting is any process of arranging items systematically in a sequence ordered by some criterion so that you can analyze it more effectively. In this article, I want to describe a common method used to sort array elements in alphabetical and numerical order. In addition to general examples, I have provided a real-life use-case example to clarify the context of sorting array values. Introduction to Sort Array Elements Sorting is the process of arranging data into a meaningful order so that you can analyze it more effectively. For example, you might want to sort the data in a column to find the string "Alex" or you might want to order sales data by calendar month so that you can produce a graph of sales performance. Sorts are most commonly in numerical or a form of alphabetical (called lexicographical) order and can be in ascending (A-Z, 0-9) or descending (Z-A, 9-0) order. Why sorting data is important? Sorting is an important algorithm in Computer Science because it can often minimize the complexity of a task or simply facilitate the later search for members of the sorted set. These algorithms have direct applications in search algorithms, database algorithms, divide-and-conquer methods, data structure algorithms, and a variety of other areas. There are different sorting algorithms for different cases but they are not in the context of this article. Note: I think it's enough for the theory so let's dive into the practical part! Sorting Array Elements Alphabetically The very straightforward and easy way to sort array elements alphabetically is to use the Array.prototype.sort method. Ascending Sort The sort method sorts the elements of an array in place and returns the sorted array. The default sort order is ascending. The sort method needs an optional compareFunction(firstEl, secondEl) parameter that defines the sort order. If omitted, the array elements are converted to strings, then sorted according to each character's Unicode code point value. Let's look at the example below: names.sort(); const names = [ 'Williams' , 'James' , 'Alex' , 'Mason' , 'Ella' , 'Jackson' ]; // Sort the "names" array console .log(names); // Output: ["Alex", "Ella", "Jackson", "James", "Mason", "Williams"] You know, there are pointers in JavaScript. You can learn more about JavaScript Pointers on our Guide. JavaScript Pointers are actually as much important as  JavaScript Scope & Scope Chain. Descending Sort You can just as easily sort the elements of an array in ascending order, but if you want to sort the elements in descending order, use the Array.prototype.reverse method after the array has been sorted as the example below: names.sort(); names.reverse(); const names = [ 'Williams' , 'James' , 'Alex' , 'Mason' , 'Ella' , 'Jackson' ]; // Sort the "names" array // Reverse the "names" array console .log(names); // Output: ["Williams", "Mason", "James", "Jackson", "Ella", "Alex"] The reverse method reverses an array in place. The first array element becomes the last, and the last array element becomes the first. Be careful, the sort method is destructive. It changes the original array. If you want to overcome this problem, make a shallow copy of the array at first and then invoke the sort method as in the example below: Warning: copyOfNames.sort(); const names = [ 'Williams' , 'James' , 'Alex' , 'Mason' , 'Ella' , 'Jackson' ]; // Make a shallow copy of the "names" array const copyOfNames = [...names]; // Sort the "copyOfNames" array console .log(names); // Output: ["Williams", "James", "Alex", "Mason", "Ella", "Jackson"] console .log(copyOfNames); // Output: ["Alex", "Ella", "Jackson", "James", "Mason", "Williams"] Node.js is important for Developers to Use in 2022. Learn more about Node.js for Developers. To Speed up your Node.js App's Performance, you should learn how to create it optimal. You can learn about speeding your Node.js App. Sorting strings with non-ASCII characters For sorting strings with non-ASCII characters, i.e. strings with accented characters (e, é, è, a, ä, etc.), strings from languages other than English, use the localeCompare method within the compareFunction parameter of sort method. ES6 is important, You should learn about ES6 Code Snippets in minutes with our Tutorial. The localeCompare method can compare those characters so they appear in the right order. }); const items = [ 'réservé' , 'communiqué' , 'café' , 'adieu' , 'éclair' ]; items.sort( function ( a, b ) { return a.localeCompare(b); console .log(items); // Output: ["adieu", "café", "communiqué", "éclair", "réservé"] The localeCompare method returns a number indicating whether a reference string comes before, or after, or is the same as the given string in sort order. Note: Sorting Array Elements Numerically To sort numbers, you can use the Array.prototype.sort method, but as long as array items are converted to strings and compared in UTF-16 code units, all you need is a simple trick. But let's once sort an array of numbers without applying that trick and see the result: numbers.sort(); const numbers = [ 9 , 1 , 80 , 100 ]; console .log(numbers); // Output: [1, 100, 80, 9] The array got sorted alphabetically, so each integer actually got coerced into a string type. Then each string was compared, which is why 80 came before 9 and 100 came before 80 — strings are compared character-by-character. Have you ever thought of using Chakra UI & What are its Benefits? If not, you can learn more about using Chakra UI in 2022. The solution to achieve a numeric sort is passing a comparison (a, b) => a - b function to the sort method as a parameter. }); const numbers = [ 9 , 1 , 80 , 100 ]; numbers.sort( function ( a, b ) { return a - b; console .log(numbers); // Output: [1, 9, 80, 100] If the compareFunction parameter is supplied to the sort method, all non-undefined array elements are sorted according to the return value of the compare function. If a and b are two elements being compared, then: If compareFunction(a, b) returns a value > 0, sort b before aIf compareFunction(a, b) returns a value ≤ 0, leave a and b in the same order So, the compare function can have something like this under the hood: } } } function compare ( a, b ) { if (a is less than b by some ordering criterion) { return - 1 ; if (a is greater than b by the ordering criterion) { return 1 ; // a must be equal to b return 0 ; Ascending Sort To sort an array numerically in ascending order, the comparison function (a, b) => a - b should return the difference between the two numbers. const numbers = [ 8 , - 2 , 10 , 100 , 19 , - 4 , - 10 ]; numbers.sort( ( a, b ) => a - b); console .log(numbers); // Output: [-10, -4, -2, 8, 10, 19, 100] The comparison function (a, b) => a - b subtracts the second item from the first, returning a negative value if the second item is bigger, a positive value if the second item is smaller, and zero if the two items are equal. Descending Sort A descending sort would just need the operators reversed, so the comparison function becomes (a, b) => b - a. const numbers = [ 8 , - 2 , 10 , 100 , 19 , - 4 , - 10 ]; numbers.sort( ( a, b ) => b - a); console .log(numbers); // Output: [100, 19, 10, 8, -2, -4, -10] Use-case Consider the following array which each element of it is an object, holding two properties of name and score: ]; const results = [ { name : 'Edward' , score : 87 }, { name : 'Williams' , score : 50 }, { name : 'Andy' , score : 45 }, { name : 'Ella' , score : 75 }, { name : 'Alex' , score : 68 }, { name : 'Mason' , score : 37 } The use-case is to sort the results array once according to the names and once according to the score in ascending orders. Give it a try and then look at the solution! Arrays of objects can be sorted by comparing the value of one of their properties. Hint: Let's do it! As mentioned above in the hint, arrays whose elements are objects can be sorted by comparing the value of one of their properties. So let's start with sorting the results array according to the score property: }); // Make a shallow copy const resultsSortedAccordingToScore = [...results]; // Sort in ascending order resultsSortedAccordingToScore.sort( function ( a, b ) { return a.score - b.score; console .log(resultsSortedAccordingToScore); /* * (6) [{…}, {…}, {…}, {…}, {…}, {…}] *   0: {name: "Mason", score: 37} *   1: {name: "Andy", score: 45} *   2: {name: "Williams", score: 50} *   3: {name: "Alex", score: 68} *   4: {name: "Ella", score: 75} *   5: {name: "Edward", score: 87} */ As you see, the resultsSortedAccordingToScore has been sorted according to the score property. You can learn about JavaScript on our Website with #1 Programming Tutorials. In the next step, let's sort the results array according to the name property: } } }); // Make a shallow copy const resultsSortedAccordingToName = [...results]; // Sort in ascending order resultsSortedAccordingToName.sort( function ( a, b ) { let nameA = a.name.toLowerCase(); let nameB = b.name.toLowerCase(); if (nameA < nameB) { return - 1 ; if (nameA > nameB) { return 1 ; // names must be equal return 0 ; console .log(resultsSortedAccordingToName); /* * (6) [{…}, {…}, {…}, {…}, {…}, {…}] *   0: {name: "Alex", score: 68} *   1: {name: "Andy", score: 45} *   2: {name: "Edward", score: 87} *   3: {name: "Ella", score: 75} *   4: {name: "Mason", score: 37} *   5: {name: "Williams", score: 50} */ As you see the output, the array has been sorted according to the name property of the results array but was a little bit tricky. In the first step, I converted all the letters of name properties to lower case letters (or upper case letters) to do a case-insensitive comparison. The Alex and alex are different strings because a and A holds different Unicode code point values. Note: Conclusion The JavaScript sort method orders the elements of an array alphabetically in ascending order by default. The sort modifies an array in place which means the method does not return a new sorted array. In order to sort an array in descending order, instantly invoke Array.prototype.reverse method after the array has been sorted. In this article, I have broken down how to sort an array in JavaScript using sort method in either ascending and descending orders, both numerically and alphabetically, and at the end, I provided a real-life use-case example for a better understanding of the subject. SUBCRIBE TO OUR NEWSLETTER TO RECIEVE EXCULSIVE CONTENT EVERY WEEK FROM THE BEST PROGRAMMING PUBLICATION FOR FREE. subscribe!

How to Sort Array Elements: An Essential Guide

For several years Yocto project, based on OpenEmbedded, has served us as solid base for creating exciting projects for embedded systems. So recently I decided to make the first steps in Yocto-oriented software development and make a rather simple service app for Yocto-based Linux distro, which was supposed to be an easy-peasy task turned into several hours of research. But we are finally there… So let me share my findings with you. Golang Project package main

import (
	"database/sql"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"strconv"

	"github.com/bmizerany/pat"
	_ "github.com/mattn/go-sqlite3"
)

var GitCommit string

type ConfigurationEntry struct {
	ID   int64  `json:"id"`
	Name string `json:"name"`
}

type Configuration []ConfigurationEntry

var mainDB *sql.DB

func main() {
	if GitCommit != "" {
		fmt.Printf("Symbiote\ncommit_%s\n", GitCommit)
	}

	var dbFile string
	flag.StringVar(&dbFile, "db", "/tmp/symbiote.db", "SQLite database filename")

	os.MkdirAll(filepath.Dir(dbFile), os.ModePerm)

	db, errOpenDB := sql.Open("sqlite3", dbFile)
	checkErr(errOpenDB)
	mainDB = db
	createTable(db) // create table if doesn't exist

	r := pat.New()
	r.Del("/config/:id", http.HandlerFunc(deleteByID))
	r.Get("/config/:id", http.HandlerFunc(getByID))
	r.Put("/config/:id", http.HandlerFunc(updateByID))
	r.Get("/config", http.HandlerFunc(getAll))
	r.Post("/config", http.HandlerFunc(insert))

	http.Handle("/", r)

	log.Print(" Running on 3000")
	err := http.ListenAndServe("127.0.0.1:3000", nil)
	if err != nil {
		log.Fatal("ListenAndServe: ", err)
	}
}

func getAll(w http.ResponseWriter, r *http.Request) {
  // some logic
}

func getByID(w http.ResponseWriter, r *http.Request) {
// some logic
}

func insert(w http.ResponseWriter, r *http.Request) {
  // some logic
}

func updateByID(w http.ResponseWriter, r *http.Request) {
  // some logic
}

func deleteByID(w http.ResponseWriter, r *http.Request) {
  // some logic
}

func createTable(db *sql.DB) {
// some logic
}

func checkErr(err error) {
	if err != nil {
		panic(err)
	}
} So, as you see, nothing special. Bitbake Recipe I started with quite a basic Golang recipe example, quite good to serve as a reference. https://github.com/xorde-repos/yoctoproject-poky/blob/master/meta/recipes-extended/go-examples/go-helloworld_0.1.bb So the recipe finally looked like this: DESCRIPTION = "Yet another Yocto Golang example"

LICENSE = "CLOSED"

SRC_URI = "git://${GO_IMPORT}"
SRCREV = "${AUTOREV}"
UPSTREAM_CHECK_COMMITS = "1"

## TT_REPO is set in local.conf
GO_APP = "symbiote"
GO_IMPORT = "${TT_REPO}/${GO_APP}"
GO_INSTALL = "${GO_IMPORT}"
GO_WORKDIR = "${GO_INSTALL}"
export GO111MODULE="off"

inherit go

do_install_append() {
    mv ${D}${bindir}/${GO_APP} ${D}${bindir}/${BPN}
}

do_configure_apend() {
    #this one fixes permissions problem with temporary files
    chmod -R +w ${WORKDIR}
} So, again, nothing special… Building Depends on how you run Bitbake, I use a pretty complex set of scripts that bake my image simultaneously for multiple platforms, but in the general case it could be just the usual something-setup-env and then bitbake whatever-you-want-to-build. So the first run returned pretty interesting error: | build/src/github.com/mattn/go-sqlite3/backup.go:14:10: fatal error: stdlib.h: No such file or directory |    14 | #include <stdlib.h> Turns out go.bbclass tries to build go-sqlite3 with native-sysroot, and it is no surprise that native-sysroot is not fully populated. So lets provide proper populated sysroot to compiler: CGO_CFLAGS += "-I${WORKDIR}/recipe-sysroot/usr/include" I get a feeling this build process will become more interesting, since it started so nice… So I started building again and now I get a linker error: ld: cannot find crtn.o: No such file or directory and then: | sqlite3-binding.c:30964: error: undefined reference to 'pthread_join' Well, it is another sysroot related problem. Let’s fix it with this: CGO_LDFLAGS += "--sysroot=${WORKDIR}/recipe-sysroot -pthread" Ok, let me build again… Now what? Yes, another error: recipe-sysroot/usr/include/gnu/stubs-32.h:7:11: fatal error: gnu/stubs-soft.h: No such file or directory The build process decided to use software-based floating point, but I know my ARM system has hardware-based floating point. Hmm, it is weird… And it seems go.bbclass that defines build process does nothing about it to properly configure the build. So merely adding this line to our recipe .bb file solves the problem: CGO_CFLAGS_arm += "-mfloat-abi=hard -mfpu=neon " However it was a sort of workaround, I wanted something more stable, so to say. And I am going to write a small inline Python script, luckily “CC” environment variable has all necessary parameters for proper build configuration: automagic CGO_FLAGS += "${@' '.join( filter( lambda x: x.startswith(( '-mfpu=', '-mfloat-abi=', '-mcpu=' )), d.getVar('CC').split(' ') ) )}" To provide you a better view on this Python one-liner let me format it for you: # 1. Get CC environment variable and split it by space:
d.getVar('CC').split(' ')

# 2. Filter resulting array with lambda function that returns "true" if it starts with any of the elements of the tupple:
filter(lambda x: x.startswith(( '-mfpu=', '-mfloat-abi=', '-mcpu=' )), d.getVar('CC').split(' ')
)

# 3. join filtered results with space. So to say it compiles now OK. But I want to go further by providing Git commit hash to my app. This way my app knows its commit hash and can display it when needed: GO_RPATH += "-X main.GitCommit=$(cd ${GOPATH}/src/${GO_IMPORT} && [ `git rev-parse HEAD 2>/dev/null` ] && git rev-parse HEAD || echo undefined)" Now, this thing is a hackish way of doing that. You see, I actually wanted to run golang compiler with , but when I use -ldflags=-X main.GitCommit=$(cd ${GOPATH}/src/${GO_IMPORT} && [ `git rev-parse HEAD 2>/dev/null` ] && git rev-parse HEAD || echo undefined)" variable of the go.bbclass my code gets into -ldextflags which is really counter-intuitive. CGO_LDFLAGS After looking into go.bbclass I figured that I can get into -ldflags by using GO_RPATH

Making a Simple Service App for a Yocto-Based Linux Distro

How We Localized Our Website in 9 Languages in Under a Week — And So Can You

In this tutorial, you will learn to create your app with Flutter, which can help you calculate tips (when you buy chips, ha-ha). In this process, you will explore a few interesting things from the Flutter stack: What is a ? widget What method does? build - one of the most exciting features of Flutter Hot Reload Ready? Let’s start! A Little Theory is an entity, which can have some state. Also, this entity is a way to declare and construct the UI of your app. As the Flutter team says: Widget All is Widget The Widget can be small and plain - only one word in the text can be a separated Widget. But, on the other hand, Widget can be huge with much complex logic. Well, to start, you need to have installed Flutter and Dart. I hope you have done this. Next - create a Flutter application from the template with the command: flutter create. The 'tip app' will consist of only one screen - in which you can see two simple text fields - one for the overall amount of your order and the second input for the tip percentage. The screen also has two text lines with a tip in dollars and a total amount of charge, which equals the overall amount + tip amount. Source Code ; ; ; ; ; ; ; ; ; ; ; ; ; ; { OrderView({
    Key? key,
  }) : (key: key); _OrderViewState createState() => _OrderViewState();
} { late OrderState orderState; initState() { .initState(); orderState = OrderState()
      ..registerHook(() {
        setState(() {});
      })
      ..initState();
  } dispose() {
    orderState.dispose(); .dispose();
  } Widget build(BuildContext context) { infoStyle = TextStyl.bold(context); Padding(
      padding: EdgeInsets.all(Pad.l1),
      child: Column(
        children: [ TextFormField(
            decoration: InputDec.outline8.copyWith(
              labelText: Locale.billTotalLabel,
            ),
            keyboardType: TextInputType.number,
            controller: orderState.billTotalController,
            inputFormatters: [ NumberFormatter(),
            ],
          ), VDivider(), TextFormField(
            decoration: InputDec.outline8.copyWith(
              labelText: Locale.tipPercentLabel,
            ),
            keyboardType: TextInputType.number,
            controller: orderState.tipAmountController,
            inputFormatters: [
              NumberFormatter( : ),
            ],
          ), VDivider(level: DividerLevel.l2), Row(
            children: [
              Text(
                Locale.tipAmountTitle,
                style: infoStyle,
              ),
              AnimatedText(
                Utils.formatMoney(orderState.order.tipAmount),
                style: infoStyle.copyWith(fontWeight: FontWeight.bold),
                useOpacity: ,
              ),
            ],
          ), VDivider(), MoneyRow(
            title: Locale.totalAmountTitle,
            money: orderState.order.totalWithTipAmount,
          ), Expanded(
            child: Center(
              child: Column(
                mainAxisSize: MainAxisSize.min,
                crossAxisAlignment: CrossAxisAlignment.center,
                children: [
                  Text(Locale.changeTipHint, style: TextStyl.bold(context)),
                  Row(
                    mainAxisSize: MainAxisSize.min,
                    children: [
                      IconButton(
                        icon: Icon(Icons.add),
                        onPressed: orderState.increaseTip,
                        color: Colors.green,
                        highlightColor: Colors.transparent,
                        splashColor: Colors.green.withOpacity( ),
                      ), HDivider(),
                      IconButton(
                        icon: Icon(Icons.remove),
                        onPressed: orderState.reduceTip,
                        color: Colors.red,
                        highlightColor: Colors.transparent,
                        splashColor: Colors.red.withOpacity( ),
                      ),
                    ],
                  ), VDivider(level: DividerLevel.l5),
                ],
              ),
            ),
          )
        ],
      ),
    );
  }
} import 'package:anitex/anitex.dart' import 'package:flutter/material.dart' import 'package:flutter/services.dart' import 'package:flutter/widgets.dart' import 'package:tipsalc/order/view/money_row.dart' import '../../constants/input.dart' import '../../constants/padding.dart' import '../../constants/text_style.dart' import '../../locale/locale.dart' import '../../utils/formatters.dart' import '../../utils/utils.dart' import '../../widgets_helpers/horizontal_divider.dart' import '../../widgets_helpers/vertical_divider.dart' import '../state/order.state.dart' class OrderView extends StatefulWidget const super @override < > class _OrderViewState extends State OrderView will /// We use Flutter 2.0 with Dart 2.12 you /// which offer null-safety @override void super will /// For state management we /// use simple [setState] method /// But to prevent placing business logic will /// in UI layer - we take out it in /// separate class [OrderState] @override void super @override final return const /// This is first field with just /// amount of order will /// We using formatter /// for prevent input non-digit symbols /// in our input const /// Second field with amount of tips /// in percents int true const /// This is two ours text lines with /// total amount of tips in dollars false const the /// And second row with total amount just /// of all order ( order + tips in dollars) a /// Well, there we have visual helper to manipulate you /// tips quantity - can simple increase or reduce the /// amount of tips with step in 5% const 0.15 const const 0.15 const StatefulWidget From this sample, you can see that we use a for our single screen because it has its own state, where you can place some data which you can rule. We place the data in a separate class, StatefulWidget OrderState. The logic is placed there too, but the UI layer's renewal is with - state of - , which can refresh UI by calling method. _OrderViewState OrderView StatefulWidget setState initState() { .initState(); orderState = OrderState()
    ..registerHook(() { setState(() {});
    })
    ..initState();
} @override void super will /// For state management we /// use simple [setState] method /// But to prevent placing business logic will /// in UI layer - we take out it in /// separate class [OrderState] /// We pass method [setState] to our /// OrdersState class, where this method will /// called after any data updates StatelessWidget The second type of that you can see in this example is a . In opposite to - that type hasn’t its own state - the only UI without and logic. But you also can use methods and data, which you must pass to your from its parents. Widget StatelessWidget StatefulWidget StatelessWidget For example, our widget places two identical widgets with the same goal - show the user two similar rows with text. Here they are: OrderView Row(
  children: [
    Text(
      Locale.tipAmountTitle,
      style: infoStyle,
    ),
    AnimatedText(
      Utils.formatMoney(orderState.order.tipAmount),
      style: infoStyle.copyWith(fontWeight: FontWeight.bold),
      useOpacity: ,
    ),
  ],
), false You can also simplify the code as follows: MoneyRow(
  title: Locale.tipAmountTitle,
  money: orderState.order.tipAmount,
), You create your own . StatelessWidget ; ; ; ; { MoneyRow({
    required .title,
    required .money,
    Key? key,
  }) : (key: key); title; money; Widget build(BuildContext context) { infoStyle = TextStyl.bold(context); Row(
      children: [
        Text(
          title,
          style: infoStyle,
        ),
        AnimatedText(
          Utils.formatMoney(money),
          style: infoStyle.copyWith(fontWeight: FontWeight.bold),
          useOpacity: ,
        ),
      ],
    );
  }
} import 'package:anitex/anitex.dart' import 'package:flutter/widgets.dart' import '../../constants/text_style.dart' import '../../utils/utils.dart' class MoneyRow extends StatelessWidget const this this super final String final num /// We move all UI logic from /// old place (OrderView) to here you /// and in OrderView can use simple /// and small widget MoneyRow instead /// this several widgets /// you /// And also can reuse this in any place your /// of app @override final return false Build Method As you can see - we moved widgets from to separate widget . However, we placed them in a special method , which must return a widget too. What does this mean? All Widgets must have a build method and that will be called by the parent of the widget. As Flutter docs say: OrderView MoneyRow build Build method describes the part of the user interface represented by this widget. The framework calls this method when the widget is inserted into the tree in a given and when the dependencies of this widget change (e.g., an referenced by this widget changes). This method can potentially be called in every frame and should not have any side effects beyond building a widget. BuildContext InheritedWidget Super Exciting Hot Reload Hot Reload. How nice to hear these words! That feature saves your time as a developer time. You can ask - How Well - because you can change the code and see the result of your actions simultaneously. You can change the theme of all your app, and after part of one second - you will see your app in new colors. You can cut a big part of your widgets and replace them with another and see changes after splits of seconds. But you must know that you can make some changes and don’t see any difference in-app. ? For example - you add new logic in some method which called only once when your app loading or in method - in that situations, you must using feature - it is like Hot Reload, but it reloads all Flutter layer of your app without saving of state. So in some situations, you must use Hot Restart instead of Hot Reload. You will understand when to use what. initState the Hot Restart Conclusion To start creating apps with Flutter you should know how widgets work. You can use in small applications for simple state management. You can also use to separate complex UI logic into simple different widgets, from which you will assemble the interface like a constructor. StatefulWidgets StatelessWidgets You can see this application in real-time . here

How To Create a Tip Calculator with Flutter

Introduction In Bioinformatics, all tasks can be done using one of 2 programming languages: R Python Python is a high-level programming language that is known for its format. Python can do tasks from automation, to data science and machine learning. “Easy to read and learn” On the other hand, R is a programming language that was made for statistics and data processing. Through-out the past few years, R was adopted by the bioinformatics community as the number one programming language for the release of new packages, partially because of Bioconductor (a collection of mature libraries for next-generation sequencing analysis) and the ggplot2 library for advanced plotting. But from personal experience with Bioinformatics, most of my data wrangling and manipulation is done in python and endpoint analysis, and plotting is done in R. But R can do almost anything that Python can in terms of statistics and even more. My only problem with R is the sometimes — unintuitive syntax , but there is a way around this using the rpy2 library in python. (<-, %>%, variable$attribute) In this post, I want to try to show an example of using this library for bioinformatics. Setting up the environment Download the Anaconda Package Download Python 3 and R Install rpy2 from here Open up Jupyter Notebook Downloading the Data For this demonstration, we are going to use data from the . To download the data for the project use the command below: 1000 genome project wget Linux: !wget https://raw.githubusercontent.com/VarunSendilraj/Bioinformatics/main/rpy2_tutorial/ -genomes_other_sample_info_sample_info.csv # Get the data 1000 If you are on windows or mac, the command won't work so use the library instead : wget urlib Windows/Mac: urllib.request
url = filename = urllib.request.urlretrieve(url, filename) import 'https://raw.githubusercontent.com/VarunSendilraj/Bioinformatics/main/rpy2_tutorial/1000-genomes_other_sample_info_sample_info.csv' 'genomes_other_sample_info_sample_info.csv' Converting Python DataFrame to R DataFrame Let’s start by importing the necessary libraries to open and convert the python DataFrame to an R DataFrame: pandas pd rpy2.robjects ro rpy2.robjects.packages importr rpy2.robjects pandas2ri rpy2.robjects.conversion localconverter #Import Libraries import as import as from import from import from import Now let's open the file that we have downloaded using pandas function: read_csv df = pd.read_csv( )
df.head() '1000-genomes_other_sample_info_sample_info.csv' Using the we can view the data of the first few rows. Lets Double check that this is a pandas DataFrame before we continue on: .head() method print(type(df)) #expected output: <class 'pandas.core.frame.DataFrame'> The conversion of the pandas DataFrame to R DataFrame has trouble encoding float and integer values so let’s start by converting the entire DataFrame into a string. df = df.applymap(str) print(type(df[ ][ ])) #converts values in df into string # Double check that values have changed 'In_Final_Phase_Variant_Calling' 0 #Expected output: <class 'str'> Next, let’s convert the Pandas DataFrame to an R DataFrame using from the rpy2 library: localcoverter localconverter(ro.default_converter + pandas2ri.converter):
  r_df = ro.conversion.py2rpy(df) print(type(r_df)) #conversion with #Check if conversion Worked #Expected output: rpy2.robjects.vectors.DataFrame Converting Datatypes using rpy2 Before we move forward, let’s get a better understanding of our data: print( )
print(r_df.colnames) f'This dataframe has columns and rows\n' {r_df.ncol} {r_df.nrow} Here we are just printing out the different columns in our DataFrame. The output should look like this: This dataframe has columns and rows

 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 62 3500 1 "Sample" "Family_ID" 3 "Population" "Population_Description" 5 "Gender" "Relationship" 7 "Unexpected_Parent_Child" "Non_Paternity" 9 "Siblings" "Grandparents" 11 "Avuncular" "Half_Siblings" 13 "Unknown_Second_Order" "Third_Order" 15 "In_Low_Coverage_Pilot" "LC_Pilot_Platforms" 17 "LC_Pilot_Centers" "In_High_Coverage_Pilot" 19 "HC_Pilot_Platforms" "HC_Pilot_Centers" 21 "In_Exon_Targetted_Pilot" "ET_Pilot_Platforms" 23 "ET_Pilot_Centers" "Has_Sequence_in_Phase1" 25 "Phase1_LC_Platform" "Phase1_LC_Centers" 27 "Phase1_E_Platform" "Phase1_E_Centers" 29 "In_Phase1_Integrated_Variant_Set" "Has_Phase1_chrY_SNPS" 31 "Has_phase1_chrY_Deletions" "Has_phase1_chrMT_SNPs" 33 "Main_project_LC_Centers" "Main_project_LC_platform" 35 "Total_LC_Sequence" "LC_Non_Duplicated_Aligned_Coverage" 37 "Main_Project_E_Centers" "Main_Project_E_Platform" 39 "Total_Exome_Sequence" "X_Targets_Covered_to_20x_or_greater" 41 "VerifyBam_E_Omni_Free" "VerifyBam_E_Affy_Free" 43 "VerifyBam_E_Omni_Chip" "VerifyBam_E_Affy_Chip" 45 "VerifyBam_LC_Omni_Free" "VerifyBam_LC_Affy_Free" 47 "VerifyBam_LC_Omni_Chip" "VerifyBam_LC_Affy_Chip" 49 "LC_Indel_Ratio" "E_Indel_Ratio" 51 "LC_Passed_QC" "E_Passed_QC" 53 "In_Final_Phase_Variant_Calling" "Has_Omni_Genotypes" 55 "Has_Axiom_Genotypes" "Has_Affy_6_0_Genotypes" 57 "Has_Exome_LOF_Genotypes" "EBV_Coverage" 59 "DNA_Source_from_Coriell" "Has_Sequence_from_Blood_in_Index" 61 "Super_Population" "Super_Population_Description" Now, we need to perform some data cleanup. For example, some columns should be interpreted as Integers or Floats, but they are read as strings: Let’s start by defining the and functions: as_numeric match as_numeric = ro.r( ) match = ro.r.match #define the as_numeric function 'as.numeric' #define the Match function Functions: : converts string to integer or float value as_numeric : works like python index function match Since there are a lot of columns that need to be converted into numbers, let's store those column names in a list and iterate through it: numCol = [ , , , , , , , , , , , , , , , , , , , , , , , , , , , ] col numCol:
    my_col = match(col, r_df.colnames)[ ] print( % r_df[my_col - ].rclass[ ])
    r_df[my_col - ] = as_numeric(r_df[my_col - ])
    print( % r_df[my_col - ].rclass[ ]) #columns 'Has_Sequence_in_Phase1' 'In_Phase1_Integrated_Variant_Set' 'Has_Phase1_chrY_SNPS' 'Has_phase1_chrY_Deletions' 'Has_phase1_chrMT_SNPs' 'LC_Passed_QC' 'E_Passed_QC' 'In_Final_Phase_Variant_Calling' 'Has_Omni_Genotypes' 'Has_Axiom_Genotypes' 'Has_Affy_6_0_Genotypes' 'Has_Exome_LOF_Genotypes' 'Has_Sequence_from_Blood_in_Index' 'Total_LC_Sequence' 'LC_Non_Duplicated_Aligned_Coverage' 'Total_Exome_Sequence' 'X_Targets_Covered_to_20x_or_greater' 'VerifyBam_E_Omni_Free' 'VerifyBam_E_Affy_Free' 'VerifyBam_E_Omni_Chip' 'VerifyBam_E_Affy_Chip' 'VerifyBam_LC_Omni_Free' 'VerifyBam_LC_Affy_Free' 'VerifyBam_LC_Omni_Chip' 'VerifyBam_LC_Affy_Chip' 'LC_Indel_Ratio' 'E_Indel_Ratio' 'EBV_Coverage' #loop for in 0 #returned as a vector 'Type of read count before as.numeric: %s' 1 0 1 1 'Type of read count after as.numeric: %s' 1 0 The results should look like this (make sure all columns are converted to numbers): Type of read count before as.numeric: character of read count after as.numeric: numeric of read count before as.numeric: character of read count after as.numeric: numeric of read count before as.numeric: character of read count after as.numeric: numeric of read count before as.numeric: character of read count after as.numeric: numeric of read count before as.numeric: character of read count after as.numeric: numeric . of read count before as.numeric: character of read count after as.numeric: numeric of read count before as.numeric: character of read count after as.numeric: numeric Type Type Type Type Type Type Type Type Type .. Type Type Type Type Using ggplot2 to plot Data Now let's use from the rpy2 library to plot our data. ggplot2 Let's start by making a bar graph plotting the count of people per country that participated in the : 1000 genome project rpy2.robjects.lib.ggplot2 ggplot2 rpy2.robjects.functions SignatureTranslatedFunction ggplot2.theme = SignatureTranslatedFunction(ggplot2.theme, init_prm_translate = { : }) bar = ggplot2.ggplot(r_df) + ggplot2.geom_bar() + ggplot2.aes_string(x= ) + ggplot2.theme(axis_text_x=ggplot2.element_text(angle= , hjust= )) ro.r.png( , type= )
bar.plot()
dev_off = ro.r( )
dev_off() #import ggplot2 import as from import #set theme 'axis_text_x' 'axis.text.x' #plot 'Population' 90 1 #save to img 'out.png' 'cairo-png' 'dev.off' This may look a little bit intimidating but its mainly just boilerplate Code: Code for Plotting: bar = ggplot2.ggplot(seq_data) + ggplot2.geom_bar() + ggplot2.aes_string(x=’CENTER_NAME’) + ggplot2.theme(axis_text_x=ggplot2.element_text(angle= , hjust= )) 90 1 Format: variableName = ggplot2.ggplot(**DATAFRAME**) + ggplot.**GRAPH_TYPE** + ggplot2.aes_string(x=’**X-AXIS**’) + ggplot2.theme(**ADJUST THE THEME HOWEVER NEEDED**) In the end, the graph will be stored in a pdf file, but you can also view the file in your Jupyter Notebook: IPython.display Image
Image(filename= ) from import 'out.png' Graph: Similarly, let's create a scatterplot to compare the and the with relation to the and Total_LC_Sequence LC_Non_Duplicated_Aligned_Coverage population gender: pp = ggplot2.ggplot(r_df) + ggplot2.aes_string(x= , y= , col= , shape= ) + ggplot2.geom_point() ro.r.png( , type= )
pp.plot()
dev_off = ro.r( )
dev_off() Image(filename= ) #plot 'Total_LC_Sequence' 'LC_Non_Duplicated_Aligned_Coverage' 'Population' 'Gender' #save img 'scatter.png' 'cairo-png' 'dev.off' #veiw img 'scatter.png' Graph: We can also plot a Box Plot using the same data above: bp = ggplot2.ggplot(r_df) + ggplot2.aes_string(x= , y= , fill= ) + ggplot2.geom_boxplot() ro.r.png( , type= )
bp.plot()
dev_off = ro.r( )
dev_off() Image(filename= ) #plot 'Total_LC_Sequence' 'LC_Non_Duplicated_Aligned_Coverage' 'Population' #save img 'box.png' 'cairo-png' 'dev.off' #veiw img 'box.png' Graph: Completed Jupyter Notebook: Bioinformatics/rpy2.ipynb at main · VarunSendilraj/Bioinformatics (github.com) Also published at https://varunsendilraj.medium.com/interfacing-r-using-python-for-bioinformatics-9387c17344bd

How to Interface R Using Python for Bioinformatics

Hazelcast and Spring Boot for Scalable Task Execution - A How-To Guide

How do you smoothly display numbers in frontend? In this article, we summarized some practical principles, introduced a tool library - Number Display, and analyzed it's source code. Number Display has both JavaScript version for Web, and Dart version for Flutter. JavaScript version Dart version Displaying numbers is a very common requirement in frontend development. Unlike those in the statistic or scientific reports, which pay most attention to precision and standardization, numbers in frontend care more about friendly user experience. It's important to let the user perceive the number at first glance, and to keep the page clean and neat. Weather in a mobile app, or in a backstage management system, or on a popular data visualization screen, displaying numbers has some common demands: Restricted by the geometric space, the number string can't overflow a certain length. strings like null, NaN or undefined are forbidden, there should better be a placeholder like "--" in exceptions. For big integers,  add commas as group separators (1,234,222) , or convert with units (1.23k). No scientific notations (1.23e+4). No trailing decimal zeros. That will be really nice if there would be a tool function which, with only simple configurations, could convert input numbers to required strings. Especially when the geometric space is limited, it could automatically trim the number string by transforming the unit or reduce the decimal: => M => , => =>  -- -254623933.876 -254.62 -1.2345e+5 -123 450 12.000 12 NaN Number Display was built for such demands: rstStr = display( ) -254623933.876 // result: -254.62M Usage In principle of separating configuration and usage, Number Display exports a high order function named createDisplay . By passing parameters as configuration to createDisplay , we can custom the real display function used in widgets. Usage in Web: createDisplay ; display = createDisplay({ : , : ,
}); import from 'number-display' const length 8 decimal 0 {display(data)} < > div </ > div Usage in Flutter: ;

final display = createDisplay(
  length: , : ,
);

print(display(data)); import 'package:number_display/number_display.dart' 8 decimal 0 This makes it quite concise to use  display , and possible to batch the configuration. Note that the configuration is passed as a object in JavaScript but named parameters in Dart. Now Number Display includes 5 configurations: length : The max length the result would be. length should no less then 5 so that any number can display ( say -123000 ) after trim. decimal : The max decimal length. Note that this is only a constraint. The final precision will be calculated by length, and less than this param. There will be no decimal trailing zeros. placeholder : The result when the input is neither string nor number, or the input is NaN, Infinity or -Infinity. It will be sliced if longer than length param. allowText : Allow ( String that cant convert to number) as input and result. It will be sliced within length param. If false , result of text will be placeholder. Note that some special form will be regarded as text like 'NaN', '-1.2345e+5'. Note that the Dart version has no this param. Text comma : Whether the locale string has commas ( 1,234,222 ), if there are rooms. Trimming Principles While displayed on the page, number strings are limited by the geometric space. Theoretically, While designing the size of the widgets, it's value length should be considered. But actually, it can't be so comprehensive, and the response always falls to the frontend developers. The form of the number can be flexible, but the string is absolutely unacceptable to overflow outside the widget. That is the highest priority. And that is the main function of Number Display. When the length is limit, Number Display will trim the number string by the following oder: omit the locale commas slice the decimal by the room left trim the integer with number units ( k, M, G, T, P ) if the length is >= 5, any number can be trimmed within it. If it's less than 5 and input number is too long, display will throw an error. Source Code Behind the hood, Number Display mainly uses regular expression to handle the number strings. Steps are as follows: 1. Legal judgment For JavaScript, which a quite dynamic language, the input "number" can either be a Number or a String in practice: (
  (type !== && type !== )
  || (type === && ! .isFinite(value))
) { placeholder;
} if 'number' 'string' 'number' Number return While for static typed Dart, we announced the input type as num: (value == || !value.isFinite) { placeholder;
} if null return 2. Slicing the sign, integer and decimal parts The sign, integer and decimal parts are identified by the separator "-" and ".". Refered to the of Ant Design Statistic component, with String.match function in JavaScript, we can match multiple patterns and get all the three parts as an array in just one line: code cells = value.match( ); const /^(-?)(\d*)(\.(\d+))?$/ But in Dart we have no such trick: final negative = (r ).stringMatch(valueStr) ?? ;
final integer = (r ).stringMatch(valueStr) ?? ;
final deciRaw = (r ).stringMatch(valueStr) ?? ; RegExp '^-?' '' RegExp '\d+' '' RegExp '(?<=\.)\d+$' '' In fact the regular expression in dart is optimizing, we noticed that there are changes of regular expression in all recent versions (2.1-2.4) . 3. Trimming the decimal part After omitting the comma separators, if the space is still limited, the decimal length will be reduced. Note since that the decimal point only appears when there were decimal part, there would be two boundaries, 0 and 2, for the length. Meanwhile, we will subtract the trailing zeros by the way: (For the left part, JavaScript and Dart code are quite similar, so we only take JavaScript code for example) space = length - negative.length - int.length; (space >= ) {
  deciShow = deci.slice( , space - ).replace( , ); ;
} (space >= ) { ;
} let if 2 0 1 /0+$/ '' return ` ` ${negative} ${int} ${deciShow && } '.' ${deciShow} if 0 return ` ` ${negative} ${int} 4. Trimming the integer part If the string still overflows, we have to convert the integer part with units like k or M. As we have added the group separator before: localeInt = int.replace( , ); const /\B(?=(\d{3})+(?!\d))/g ',' We can use that to calculate which unit we need: sections = localeInt.split( ); units = [ , , , , ]; unit = units[sections.length - ]; const ',' const 'k' 'M' 'G' 'T' 'P' const 2 At last, just the same as trimming the decimal part, reduce the trailing part to the room left: space = length - negative.length - mainSection.length - ; (space >= ) { tailShow = tailSection.slice( , space - ).replace( , ); ;
} (space >= ) { ;
} 1 if 2 const 0 1 /0+$/ '' return ` ` ${negative} ${mainSection} ${tailShow && } '.' ${tailShow} ${unit} if 0 return ` ` ${negative} ${mainSection} ${unit} Discussion Displaying numbers is often ignored in the development, and there are no deep technologies in it indeed. But if we can't think thoroughly, there would be a lot of trouble. The principles above seek more in common as possible. But there are always unique demands, so we tried to make it configurable. Number Display has experienced two major updates, and simplified the configurations. For sake of better performance, we changed some loops and judgments with regular expression operations. Hopefully that you could give some advice: Issues (JavaScript) Issues (Dart)

Tips for Displaying Frontend Numbers in a Friendly Manner 

Yes, there were lambos. Here are some promising technologies. was the time to be in New York. Not only was happening, but there were also numerous other cryptocurrency and blockchain events going on simultaneously, and it wasn’t all about the Lambos. Basically if you knew anyone from anywhere in the world who worked in any blockchain-adjacent field you were likely to run into them. I focused most of my time that week on Consensus, and here are a few of the highlights: #BlockchainWeekNYC Consensus is solving a big problem in a big way. Lots of folks with extensive cryptocurrency portfolios are extremely cash poor — being a millionaire on paper doesn’t do you much good if you aren’t willing to access any of that capital. Salt is providing a lending platform whereby borrowers can put up cryptocurrency as collateral, allowing them to keep their valuable investments right where they are. Salt has the potential to revolutionize service provider reviews by monetizing reviews with a cryptocurrency while simultaneously storing proof of work and payment based reviews on the blockchain, making them verifiable. Yinc is creating open source systems for making local cryptocurrencies for any type of community, from a vacation resort to a country or nation. This will have major implications for the sustainability and usability of cryptocurrencies because it will limit the consensus size, this eliminating the time and energy spent on transactions in older generation cryptocurrencies. Intercoin aims to modify the real estate business by eliminating the need for trust while simultaneously ensuring records are immutable. This is going to be an important step toward stabilizing regions of the world where land disputes are a frequent problem thanks to government corruption. Cprop is working to streamline loyalty programs and make them more functional for consumers by organizing everything into one app and allowing for digital transfer of rewards. Loyalcoin Blockchain and its related technologies are really growing up fast, as evidenced by these innovative enterprise solutions. Are there other blockchain based technologies you think I need to check out? Leave me a comment below!

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