1652006520

How To Apply a Cinematic Color Grade in Photoshop

Learn this simple yet powerful technique to apply a Cinematic Color Grade in Photoshop!

This tutorial is part of my Photoshop in-app tutorials. You can open the tutorial image directly from Photoshop and follow the coach mark overlays to follow along. You will need Photoshop 2021 (22.5) and newer.

In this tutorial, we will use the easy sliders in the Selective Color Adjustment Layer as a filter, to apply the blue/orange cinematic look.

00:00 - Introduction
00:15 - Photoshop In-App Tutorials
01:29 - Cinematic Color Grading Explanation
02:00 - Apply Blues and Cyans to the Midtones
03:05 - Reduce Blue and Cyan from Skintones
04:05 - Make the Colors Pop with Vibrance
04:50 - Final Thoughts

#photoshop

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How To Apply a Cinematic Color Grade in Photoshop

Flutter Dev

1679035563

How to Add Splash Screen in Android and iOS with Flutter

When your app is opened, there is a brief time while the native app loads Flutter. By default, during this time, the native app displays a white splash screen. This package automatically generates iOS, Android, and Web-native code for customizing this native splash screen background color and splash image. Supports dark mode, full screen, and platform-specific options.

What's New

[BETA] Support for flavors is in beta. Currently only Android and iOS are supported. See instructions below.

You can now keep the splash screen up while your app initializes! No need for a secondary splash screen anymore. Just use the preserve and remove methods together to remove the splash screen after your initialization is complete. See details below.

Usage

Would you prefer a video tutorial instead? Check out Johannes Milke's tutorial.

First, add flutter_native_splash as a dependency in your pubspec.yaml file.

dependencies:
  flutter_native_splash: ^2.2.19

Don't forget to flutter pub get.

1. Setting the splash screen

Customize the following settings and add to your project's pubspec.yaml file or place in a new file in your root project folder named flutter_native_splash.yaml.

flutter_native_splash:
  # This package generates native code to customize Flutter's default white native splash screen
  # with background color and splash image.
  # Customize the parameters below, and run the following command in the terminal:
  # flutter pub run flutter_native_splash:create
  # To restore Flutter's default white splash screen, run the following command in the terminal:
  # flutter pub run flutter_native_splash:remove

  # color or background_image is the only required parameter.  Use color to set the background
  # of your splash screen to a solid color.  Use background_image to set the background of your
  # splash screen to a png image.  This is useful for gradients. The image will be stretch to the
  # size of the app. Only one parameter can be used, color and background_image cannot both be set.
  color: "#42a5f5"
  #background_image: "assets/background.png"

  # Optional parameters are listed below.  To enable a parameter, uncomment the line by removing
  # the leading # character.

  # The image parameter allows you to specify an image used in the splash screen.  It must be a
  # png file and should be sized for 4x pixel density.
  #image: assets/splash.png

  # The branding property allows you to specify an image used as branding in the splash screen.
  # It must be a png file. It is supported for Android, iOS and the Web.  For Android 12,
  # see the Android 12 section below.
  #branding: assets/dart.png

  # To position the branding image at the bottom of the screen you can use bottom, bottomRight,
  # and bottomLeft. The default values is bottom if not specified or specified something else.
  #branding_mode: bottom

  # The color_dark, background_image_dark, image_dark, branding_dark are parameters that set the background
  # and image when the device is in dark mode. If they are not specified, the app will use the
  # parameters from above. If the image_dark parameter is specified, color_dark or
  # background_image_dark must be specified.  color_dark and background_image_dark cannot both be
  # set.
  #color_dark: "#042a49"
  #background_image_dark: "assets/dark-background.png"
  #image_dark: assets/splash-invert.png
  #branding_dark: assets/dart_dark.png

  # Android 12 handles the splash screen differently than previous versions.  Please visit
  # https://developer.android.com/guide/topics/ui/splash-screen
  # Following are Android 12 specific parameter.
  android_12:
    # The image parameter sets the splash screen icon image.  If this parameter is not specified,
    # the app's launcher icon will be used instead.
    # Please note that the splash screen will be clipped to a circle on the center of the screen.
    # App icon with an icon background: This should be 960×960 pixels, and fit within a circle
    # 640 pixels in diameter.
    # App icon without an icon background: This should be 1152×1152 pixels, and fit within a circle
    # 768 pixels in diameter.
    #image: assets/android12splash.png

    # Splash screen background color.
    #color: "#42a5f5"

    # App icon background color.
    #icon_background_color: "#111111"

    # The branding property allows you to specify an image used as branding in the splash screen.
    #branding: assets/dart.png

    # The image_dark, color_dark, icon_background_color_dark, and branding_dark set values that
    # apply when the device is in dark mode. If they are not specified, the app will use the
    # parameters from above.
    #image_dark: assets/android12splash-invert.png
    #color_dark: "#042a49"
    #icon_background_color_dark: "#eeeeee"

  # The android, ios and web parameters can be used to disable generating a splash screen on a given
  # platform.
  #android: false
  #ios: false
  #web: false

  # Platform specific images can be specified with the following parameters, which will override
  # the respective parameter.  You may specify all, selected, or none of these parameters:
  #color_android: "#42a5f5"
  #color_dark_android: "#042a49"
  #color_ios: "#42a5f5"
  #color_dark_ios: "#042a49"
  #color_web: "#42a5f5"
  #color_dark_web: "#042a49"
  #image_android: assets/splash-android.png
  #image_dark_android: assets/splash-invert-android.png
  #image_ios: assets/splash-ios.png
  #image_dark_ios: assets/splash-invert-ios.png
  #image_web: assets/splash-web.png
  #image_dark_web: assets/splash-invert-web.png
  #background_image_android: "assets/background-android.png"
  #background_image_dark_android: "assets/dark-background-android.png"
  #background_image_ios: "assets/background-ios.png"
  #background_image_dark_ios: "assets/dark-background-ios.png"
  #background_image_web: "assets/background-web.png"
  #background_image_dark_web: "assets/dark-background-web.png"
  #branding_android: assets/brand-android.png
  #branding_dark_android: assets/dart_dark-android.png
  #branding_ios: assets/brand-ios.png
  #branding_dark_ios: assets/dart_dark-ios.png

  # The position of the splash image can be set with android_gravity, ios_content_mode, and
  # web_image_mode parameters.  All default to center.
  #
  # android_gravity can be one of the following Android Gravity (see
  # https://developer.android.com/reference/android/view/Gravity): bottom, center,
  # center_horizontal, center_vertical, clip_horizontal, clip_vertical, end, fill, fill_horizontal,
  # fill_vertical, left, right, start, or top.
  #android_gravity: center
  #
  # ios_content_mode can be one of the following iOS UIView.ContentMode (see
  # https://developer.apple.com/documentation/uikit/uiview/contentmode): scaleToFill,
  # scaleAspectFit, scaleAspectFill, center, top, bottom, left, right, topLeft, topRight,
  # bottomLeft, or bottomRight.
  #ios_content_mode: center
  #
  # web_image_mode can be one of the following modes: center, contain, stretch, and cover.
  #web_image_mode: center

  # The screen orientation can be set in Android with the android_screen_orientation parameter.
  # Valid parameters can be found here:
  # https://developer.android.com/guide/topics/manifest/activity-element#screen
  #android_screen_orientation: sensorLandscape

  # To hide the notification bar, use the fullscreen parameter.  Has no effect in web since web
  # has no notification bar.  Defaults to false.
  # NOTE: Unlike Android, iOS will not automatically show the notification bar when the app loads.
  #       To show the notification bar, add the following code to your Flutter app:
  #       WidgetsFlutterBinding.ensureInitialized();
  #       SystemChrome.setEnabledSystemUIOverlays([SystemUiOverlay.bottom, SystemUiOverlay.top]);
  #fullscreen: true

  # If you have changed the name(s) of your info.plist file(s), you can specify the filename(s)
  # with the info_plist_files parameter.  Remove only the # characters in the three lines below,
  # do not remove any spaces:
  #info_plist_files:
  #  - 'ios/Runner/Info-Debug.plist'
  #  - 'ios/Runner/Info-Release.plist'

2. Run the package

After adding your settings, run the following command in the terminal:

flutter pub run flutter_native_splash:create

When the package finishes running, your splash screen is ready.

To specify the YAML file location just add --path with the command in the terminal:

flutter pub run flutter_native_splash:create --path=path/to/my/file.yaml

3. Set up app initialization (optional)

By default, the splash screen will be removed when Flutter has drawn the first frame. If you would like the splash screen to remain while your app initializes, you can use the preserve() and remove() methods together. Pass the preserve() method the value returned from WidgetsFlutterBinding.ensureInitialized() to keep the splash on screen. Later, when your app has initialized, make a call to remove() to remove the splash screen.

import 'package:flutter_native_splash/flutter_native_splash.dart';

void main() {
  WidgetsBinding widgetsBinding = WidgetsFlutterBinding.ensureInitialized();
  FlutterNativeSplash.preserve(widgetsBinding: widgetsBinding);
  runApp(const MyApp());
}

// whenever your initialization is completed, remove the splash screen:
    FlutterNativeSplash.remove();

NOTE: If you do not need to use the preserve() and remove() methods, you can place the flutter_native_splash dependency in the dev_dependencies section of pubspec.yaml.

4. Support the package (optional)

If you find this package useful, you can support it for free by giving it a thumbs up at the top of this page. Here's another option to support the package:

Android 12+ Support

Android 12 has a new method of adding splash screens, which consists of a window background, icon, and the icon background. Note that a background image is not supported.

Be aware of the following considerations regarding these elements:

1: image parameter. By default, the launcher icon is used:

App icon without an icon background, as shown on the left: This should be 1152×1152 pixels, and fit within a circle 768 pixels in diameter.
App icon with an icon background, as shown on the right: This should be 960×960 pixels, and fit within a circle 640 pixels in diameter.

2: icon_background_color is optional, and is useful if you need more contrast between the icon and the window background.

3: One-third of the foreground is masked.

4: color the window background consists of a single opaque color.

PLEASE NOTE: The splash screen may not appear when you launch the app from Android Studio on API 31. However, it should appear when you launch by clicking on the launch icon in Android. This seems to be resolved in API 32+.

PLEASE NOTE: There are a number of reports that non-Google launchers do not display the launch image correctly. If the launch image does not display correctly, please try the Google launcher to confirm that this package is working.

PLEASE NOTE: The splash screen does not appear when you launch the app from a notification. Apparently this is the intended behavior on Android 12: core-splashscreen Icon not shown when cold launched from notification.

Flavor Support

If you have a project setup that contains multiple flavors or environments, and you created more than one flavor this would be a feature for you.

Instead of maintaining multiple files and copy/pasting images, you can now, using this tool, create different splash screens for different environments.

Pre-requirements

In order to use the new feature, and generate the desired splash images for you app, a couple of changes are required.

If you want to generate just one flavor and one file you would use either options as described in Step 1. But in order to setup the flavors, you will then be required to move all your setup values to the flutter_native_splash.yaml file, but with a prefix.

Let's assume for the rest of the setup that you have 3 different flavors, Production, Acceptance, Development.

First this you will need to do is to create a different setup file for all 3 flavors with a suffix like so:

flutter_native_splash-production.yaml
flutter_native_splash-acceptance.yaml
flutter_native_splash-development.yaml

You would setup those 3 files the same way as you would the one, but with different assets depending on which environment you would be generating. For example (Note: these are just examples, you can use whatever setup you need for your project that is already supported by the package):

# flutter_native_splash-development.yaml
flutter_native_splash:
  color: "#ffffff"
  image: assets/logo-development.png
  branding: assets/branding-development.png
  color_dark: "#121212"
  image_dark: assets/logo-development.png
  branding_dark: assets/branding-development.png

  android_12:
    image: assets/logo-development.png
    icon_background_color: "#ffffff"
    image_dark: assets/logo-development.png
    icon_background_color_dark: "#121212"

  web: false

# flutter_native_splash-acceptance.yaml
flutter_native_splash:
  color: "#ffffff"
  image: assets/logo-acceptance.png
  branding: assets/branding-acceptance.png
  color_dark: "#121212"
  image_dark: assets/logo-acceptance.png
  branding_dark: assets/branding-acceptance.png

  android_12:
    image: assets/logo-acceptance.png
    icon_background_color: "#ffffff"
    image_dark: assets/logo-acceptance.png
    icon_background_color_dark: "#121212"

  web: false

# flutter_native_splash-production.yaml
flutter_native_splash:
  color: "#ffffff"
  image: assets/logo-production.png
  branding: assets/branding-production.png
  color_dark: "#121212"
  image_dark: assets/logo-production.png
  branding_dark: assets/branding-production.png

  android_12:
    image: assets/logo-production.png
    icon_background_color: "#ffffff"
    image_dark: assets/logo-production.png
    icon_background_color_dark: "#121212"

  web: false

Great, now comes the fun part running the new command!

The new command is:

# If you have a flavor called production you would do this:
flutter pub run flutter_native_splash:create --flavor production

# For a flavor with a name staging you would provide it's name like so:
flutter pub run flutter_native_splash:create --flavor staging

# And if you have a local version for devs you could do that:
flutter pub run flutter_native_splash:create --flavor development

Android setup

You're done! No, really, Android doesn't need any additional setup.

Note: If it didn't work, please make sure that your flavors are named the same as your config files, otherwise the setup will not work.

iOS setup

iOS is a bit tricky, so hang tight, it might look scary but most of the steps are just a single click, explained as much as possible to lower the possibility of mistakes.

When you run the new command, you will need to open xCode and follow the steps bellow:

Assumption

In order for this setup to work, you would already have 3 different schemes setup; production, acceptance and development.

Preparation

Open the iOS Flutter project in Xcode (open the Runner.xcworkspace)
Find the newly created Storyboard files at the same location where the original is {project root}/ios/Runner/Base.lproj
Select all of them and drag and drop into Xcode, directly to the left hand side where the current LaunchScreen.storyboard is located already
After you drop your files there Xcode will ask you to link them, make sure you select 'Copy if needed'
This part is done, you have linked the newly created storyboards in your project.

xCode

Xcode still doesn't know how to use them, so we need to specify for all the current flavors (schemes) which file to use and to use that value inside the Info.plist file.

Open the iOS Flutter project in Xcode (open the Runner.xcworkspace)
Click the Runner project in the top left corner (usually the first item in the list)
In the middle part of the screen, on the left side, select the Runner target
On the top part of the screen select Build Settings
Make sure that 'All' and 'Combined' are selected
Next to 'Combine' you have a '+' button, press it and select 'Add User-Defined Setting'
Once you do that Xcode will create a new variable for you to name. Suggestion is to name it LAUNCH_SCREEN_STORYBOARD
Once you do that, you will have the option to define a specific name for each flavor (scheme) that you have defined in the project. Make sure that you input the exact name of the LaunchScreen.storyboard that was created by this tool
- Example: If you have a flavor Development, there is a Storyboard created name LaunchScreenDevelopment.storyboard, please add that name (without the storyboard part) to the variable value next to the flavor value
After you finish with that, you need to update Info.plist file to link the newly created variable so that it's used correctly
Open the Info.plist file
Find the entry called 'Launch screen interface file base name'
The default value is 'LaunchScreen', change that to the variable name that you create previously. If you follow these steps exactly, it would be LAUNCH_SCREEN_STORYBOARD, so input this $(LAUNCH_SCREEN_STORYBOARD)
And your done!

Congrats you finished your setup for multiple flavors,

FAQs

I got the error "A splash screen was provided to Flutter, but this is deprecated."

This message is not related to this package but is related to a change in how Flutter handles splash screens in Flutter 2.5. It is caused by having the following code in your android/app/src/main/AndroidManifest.xml, which was included by default in previous versions of Flutter:

<meta-data
 android:name="io.flutter.embedding.android.SplashScreenDrawable"
 android:resource="@drawable/launch_background"
 />

The solution is to remove the above code. Note that this will also remove the fade effect between the native splash screen and your app.

Are animations/lottie/GIF images supported?

Not at this time. PRs are always welcome!

I got the error AAPT: error: style attribute 'android:attr/windowSplashScreenBackground' not found

This attribute is only found in Android 12, so if you are getting this error, it means your project is not fully set up for Android 12. Did you update your app's build configuration?

I see a flash of the wrong splash screen on iOS

This is caused by an iOS splash caching bug, which can be solved by uninstalling your app, powering off your device, power back on, and then try reinstalling.

I see a white screen between splash screen and app

It may be caused by an iOS splash caching bug, which can be solved by uninstalling your app, powering off your device, power back on, and then try reinstalling.
It may be caused by the delay due to initialization in your app. To solve this, put any initialization code in the removeAfter method.

Can I base light/dark mode on app settings?

No. This package creates a splash screen that is displayed before Flutter is loaded. Because of this, when the splash screen loads, internal app settings are not available to the splash screen. Unfortunately, this means that it is impossible to control light/dark settings of the splash from app settings.

Notes

If the splash screen was not updated correctly on iOS or if you experience a white screen before the splash screen, run flutter clean and recompile your app. If that does not solve the problem, delete your app, power down the device, power up the device, install and launch the app as per this StackOverflow thread.

This package modifies launch_background.xml and styles.xml files on Android, LaunchScreen.storyboard and Info.plist on iOS, and index.html on Web. If you have modified these files manually, this plugin may not work properly. Please open an issue if you find any bugs.

How it works

Android

Your splash image will be resized to mdpi, hdpi, xhdpi, xxhdpi and xxxhdpi drawables.
An <item> tag containing a <bitmap> for your splash image drawable will be added in launch_background.xml
Background color will be added in colors.xml and referenced in launch_background.xml.
Code for full screen mode toggle will be added in styles.xml.
Dark mode variants are placed in drawable-night, values-night, etc. resource folders.

iOS

Your splash image will be resized to @3x and @2x images.
Color and image properties will be inserted in LaunchScreen.storyboard.
The background color is implemented by using a single-pixel png file and stretching it to fit the screen.
Code for hidden status bar toggle will be added in Info.plist.

Web

A web/splash folder will be created for splash screen images and CSS files.
Your splash image will be resized to 1x, 2x, 3x, and 4x sizes and placed in web/splash/img.
The splash style sheet will be added to the app's web/index.html, as well as the HTML for the splash pictures.

Acknowledgments

This package was originally created by Henrique Arthur and it is currently maintained by Jon Hanson.

Bugs or Requests

If you encounter any problems feel free to open an issue. If you feel the library is missing a feature, please raise a ticket. Pull request are also welcome.

Use this package as a library

Depend on it

Run this command:

With Flutter:

 $ flutter pub add flutter_native_splash

This will add a line like this to your package's pubspec.yaml (and run an implicit flutter pub get):

dependencies:
  flutter_native_splash: ^2.2.19

Alternatively, your editor might support flutter pub get. Check the docs for your editor to learn more.

Import it

Now in your Dart code, you can use:

import 'package:flutter_native_splash/flutter_native_splash.dart';

example/lib/main.dart

import 'package:flutter/material.dart';
import 'package:flutter_native_splash/flutter_native_splash.dart';

void main() {
  WidgetsBinding widgetsBinding = WidgetsFlutterBinding.ensureInitialized();
  FlutterNativeSplash.preserve(widgetsBinding: widgetsBinding);
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  void initState() {
    super.initState();
    initialization();
  }

  void initialization() async {
    // This is where you can initialize the resources needed by your app while
    // the splash screen is displayed.  Remove the following example because
    // delaying the user experience is a bad design practice!
    // ignore_for_file: avoid_print
    print('ready in 3...');
    await Future.delayed(const Duration(seconds: 1));
    print('ready in 2...');
    await Future.delayed(const Duration(seconds: 1));
    print('ready in 1...');
    await Future.delayed(const Duration(seconds: 1));
    print('go!');
    FlutterNativeSplash.remove();
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also a layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in Android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headlineMedium,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

Download Details:

Author: jonbhanson
Download Link: Download The Source Code
Official Website: https://github.com/jonbhanson/flutter_native_splash
License: MIT license

#flutter #ios #android

Aliyah Murray

1652006520

How To Apply a Cinematic Color Grade in Photoshop

Learn this simple yet powerful technique to apply a Cinematic Color Grade in Photoshop!

In this tutorial, we will use the easy sliders in the Selective Color Adjustment Layer as a filter, to apply the blue/orange cinematic look.

#photoshop

Edward Jackson

1653377002

PySpark Cheat Sheet: Spark in Python

This PySpark cheat sheet with code samples covers the basics like initializing Spark in Python, loading data, sorting, and repartitioning.

Apache Spark is generally known as a fast, general and open-source engine for big data processing, with built-in modules for streaming, SQL, machine learning and graph processing. It allows you to speed analytic applications up to 100 times faster compared to technologies on the market today. You can interface Spark with Python through "PySpark". This is the Spark Python API exposes the Spark programming model to Python.

Even though working with Spark will remind you in many ways of working with Pandas DataFrames, you'll also see that it can be tough getting familiar with all the functions that you can use to query, transform, inspect, ... your data. What's more, if you've never worked with any other programming language or if you're new to the field, it might be hard to distinguish between RDD operations.

Let's face it, map() and flatMap() are different enough, but it might still come as a challenge to decide which one you really need when you're faced with them in your analysis. Or what about other functions, like reduce() and reduceByKey()?

PySpark cheat sheet

Even though the documentation is very elaborate, it never hurts to have a cheat sheet by your side, especially when you're just getting into it.

This PySpark cheat sheet covers the basics, from initializing Spark and loading your data, to retrieving RDD information, sorting, filtering and sampling your data. But that's not all. You'll also see that topics such as repartitioning, iterating, merging, saving your data and stopping the SparkContext are included in the cheat sheet.

Note that the examples in the document take small data sets to illustrate the effect of specific functions on your data. In real life data analysis, you'll be using Spark to analyze big data.

PySpark is the Spark Python API that exposes the Spark programming model to Python.

Initializing Spark

SparkContext

>>> from pyspark import SparkContext
>>> sc = SparkContext(master = 'local[2]')

Inspect SparkContext

>>> sc.version #Retrieve SparkContext version
>>> sc.pythonVer #Retrieve Python version
>>> sc.master #Master URL to connect to
>>> str(sc.sparkHome) #Path where Spark is installed on worker nodes
>>> str(sc.sparkUser()) #Retrieve name of the Spark User running SparkContext
>>> sc.appName #Return application name
>>> sc.applicationld #Retrieve application ID
>>> sc.defaultParallelism #Return default level of parallelism
>>> sc.defaultMinPartitions #Default minimum number of partitions for RDDs

Configuration

>>> from pyspark import SparkConf, SparkContext
>>> conf = (SparkConf()
     .setMaster("local")
     .setAppName("My app")
     . set   ("spark. executor.memory",   "lg"))
>>> sc = SparkContext(conf = conf)

Using the Shell

In the PySpark shell, a special interpreter-aware SparkContext is already created in the variable called sc.

$ ./bin/spark-shell --master local[2]
$ ./bin/pyspark --master local[s] --py-files code.py

Set which master the context connects to with the --master argument, and add Python .zip..egg or.py files to the

runtime path by passing a comma-separated list to --py-files.

Loading Data

Parallelized Collections

>>> rdd = sc.parallelize([('a',7),('a',2),('b',2)])
>>> rdd2 = sc.parallelize([('a',2),('d',1),('b',1)])
>>> rdd3 = sc.parallelize(range(100))
>>> rdd = sc.parallelize([("a",["x","y","z"]),
               ("b" ["p","r,"])])

External Data

Read either one text file from HDFS, a local file system or any Hadoop-supported file system URI with textFile(), or read in a directory of text files with wholeTextFiles().

>>> textFile = sc.textFile("/my/directory/•.txt")
>>> textFile2 = sc.wholeTextFiles("/my/directory/")

Retrieving RDD Information

Basic Information

>>> rdd.getNumPartitions() #List the number of partitions
>>> rdd.count() #Count RDD instances 3
>>> rdd.countByKey() #Count RDD instances by key
defaultdict(<type 'int'>,{'a':2,'b':1})
>>> rdd.countByValue() #Count RDD instances by value
defaultdict(<type 'int'>,{('b',2):1,('a',2):1,('a',7):1})
>>> rdd.collectAsMap() #Return (key,value) pairs as a dictionary
   {'a': 2, 'b': 2}
>>> rdd3.sum() #Sum of RDD elements 4950
>>> sc.parallelize([]).isEmpty() #Check whether RDD is empty
True

Summary

>>> rdd3.max() #Maximum value of RDD elements 
99
>>> rdd3.min() #Minimum value of RDD elements
0
>>> rdd3.mean() #Mean value of RDD elements 
49.5
>>> rdd3.stdev() #Standard deviation of RDD elements 
28.866070047722118
>>> rdd3.variance() #Compute variance of RDD elements 
833.25
>>> rdd3.histogram(3) #Compute histogram by bins
([0,33,66,99],[33,33,34])
>>> rdd3.stats() #Summary statistics (count, mean, stdev, max & min)

Applying Functions

#Apply a function to each RFD element
>>> rdd.map(lambda x: x+(x[1],x[0])).collect()
[('a' ,7,7, 'a'),('a' ,2,2, 'a'), ('b' ,2,2, 'b')]
#Apply a function to each RDD element and flatten the result
>>> rdd5 = rdd.flatMap(lambda x: x+(x[1],x[0]))
>>> rdd5.collect()
['a',7 , 7 ,  'a' , 'a' , 2,  2,  'a', 'b', 2 , 2, 'b']
#Apply a flatMap function to each (key,value) pair of rdd4 without changing the keys
>>> rdds.flatMapValues(lambda x: x).collect()
[('a', 'x'), ('a', 'y'), ('a', 'z'),('b', 'p'),('b', 'r')]

Selecting Data

Getting

>>> rdd.collect() #Return a list with all RDD elements 
[('a', 7), ('a', 2), ('b', 2)]
>>> rdd.take(2) #Take first 2 RDD elements 
[('a', 7),  ('a', 2)]
>>> rdd.first() #Take first RDD element
('a', 7)
>>> rdd.top(2) #Take top 2 RDD elements 
[('b', 2), ('a', 7)]

Sampling

>>> rdd3.sample(False, 0.15, 81).collect() #Return sampled subset of rdd3
     [3,4,27,31,40,41,42,43,60,76,79,80,86,97]

Filtering

>>> rdd.filter(lambda x: "a" in x).collect() #Filter the RDD
[('a',7),('a',2)]
>>> rdd5.distinct().collect() #Return distinct RDD values
['a' ,2, 'b',7]
>>> rdd.keys().collect() #Return (key,value) RDD's keys
['a',  'a',  'b']

Iterating

>>> def g (x): print(x)
>>> rdd.foreach(g) #Apply a function to all RDD elements
('a', 7)
('b', 2)
('a', 2)

Reshaping Data

Reducing

>>> rdd.reduceByKey(lambda x,y : x+y).collect() #Merge the rdd values for each key
[('a',9),('b',2)]
>>> rdd.reduce(lambda a, b: a+ b) #Merge the rdd values
('a', 7, 'a' , 2 , 'b' , 2)

Grouping by

>>> rdd3.groupBy(lambda x: x % 2) #Return RDD of grouped values
          .mapValues(list)
          .collect()
>>> rdd.groupByKey() #Group rdd by key
          .mapValues(list)
          .collect() 
[('a',[7,2]),('b',[2])]

Aggregating

>> seqOp = (lambda x,y: (x[0]+y,x[1]+1))
>>> combOp = (lambda x,y:(x[0]+y[0],x[1]+y[1]))
#Aggregate RDD elements of each partition and then the results
>>> rdd3.aggregate((0,0),seqOp,combOp) 
(4950,100)
#Aggregate values of each RDD key
>>> rdd.aggregateByKey((0,0),seqop,combop).collect() 
     [('a',(9,2)), ('b',(2,1))]
#Aggregate the elements of each partition, and then the results
>>> rdd3.fold(0,add)
     4950
#Merge the values for each key
>>> rdd.foldByKey(0, add).collect()
[('a' ,9), ('b' ,2)]
#Create tuples of RDD elements by applying a function
>>> rdd3.keyBy(lambda x: x+x).collect()

Mathematical Operations

>>>> rdd.subtract(rdd2).collect() #Return each rdd value not contained in rdd2
[('b' ,2), ('a' ,7)]
#Return each (key,value) pair of rdd2 with no matching key in rdd
>>> rdd2.subtractByKey(rdd).collect()
[('d', 1)1
>>>rdd.cartesian(rdd2).collect() #Return the Cartesian product of rdd and rdd2

Sort

>>> rdd2.sortBy(lambda x: x[1]).collect() #Sort RDD by given function
[('d',1),('b',1),('a',2)]
>>> rdd2.sortByKey().collect() #Sort (key, value) ROD by key
[('a' ,2), ('b' ,1), ('d' ,1)]

Repartitioning

>>> rdd.repartition(4) #New RDD with 4 partitions
>>> rdd.coalesce(1) #Decrease the number of partitions in the RDD to 1

Saving

>>> rdd.saveAsTextFile("rdd.txt")
>>> rdd.saveAsHadoopFile("hdfs:// namenodehost/parent/child",
               'org.apache.hadoop.mapred.TextOutputFormat')

Stopping SparkContext

>>> sc.stop()

Execution

$ ./bin/spark-submit examples/src/main/python/pi.py

Have this Cheat Sheet at your fingertips

Original article source at https://www.datacamp.com

#pyspark #cheatsheet #spark #python

Beth Cooper

1659701760

Fast Read and Highly Scalable Optimized Social Activity Feed in Ruby

SimpleFeed

1. Scalable, Easy to Use Activity Feed Implementation.

Note	please feel free to read this README in the formatted-for-print PDF Version.

1.1. Build & Gem Status

1.2. Test Coverage Map

Coverage Map

Important

Please read the (somewhat outdated) blog post Feeding Frenzy with SimpleFeed launching this library. Please leave comments or questions in the discussion thread at the bottom of that post. Thanks!

If you like to see this project grow, your donation of any amount is much appreciated.

Donate

This is a fast, pure-ruby implementation of an activity feed concept commonly used in social networking applications. The implementation is optimized for read-time performance and high concurrency (lots of users), and can be extended with custom backend providers. One data provider come bundled: the production-ready Redis provider.

Important Notes and Acknowledgements:

SimpleFeed does not depend on Ruby on Rails and is a pure-ruby implementation

SimpleFeed requires MRI Ruby 2.3 or later

SimpleFeed is currently live in production

SimpleFeed is open source thanks to the generosity of Simbi, Inc.

2. Features

SimpleFeed is a Ruby Library that can be plugged into any application to power a fast, Redis-based activity feed implementation so common on social networking sites. SimpleFeed offers the following features:

Modelled after graph-relationships similar to those on Twitter (bi-directional independent follow relationships):

Feed maintains a reverse-chronological order for heterogeneous events for each user.

It offers a constant time lookup for user’s feed, avoiding complex SQL joins to render it.

An API to read/paginate the feed for a given user

As well as to query the total unread items in the feed since it was last read by the user (typically shown on App icons).

Scalable and well performing Redis-based activity feed —

Scales to millions of users (will need to use Twemproxy to shard across several Redis instances)

Stores a fixed number of events for each unique "user" — the default is 1000. When the feed reaches 1001 events, the oldest event is offloaded from the activity.

Implementation properties:

Fully thread-safe implementation, writing events can be done in eg. Sidekiq.

Zero assumptions about what you are storing: the "data" is just a string. Serialize it with JSON, Marshall, YAML, or whatever.

You can create as many different types of feeds per application as you like (no Ruby Singletons used).

Customize mapping from user_id to the activity id based on your business logic (more on this later).

2.1. Publishing Events

Pushing events to the feed requires the following:

An Event consisting of:

String data that, most commonly, is a foreign key to a database table, but can really be anything you like.

Float at (typically, the timestamp, but can be any float number)

One or more user IDs, or event consumers: basically — who should see the event being published in their feed.

You publish an event by choosing a set of users whose feed should be updated. For example, were you re-implementing Twitter, your array of user_ids when publishing an event would be all followers of the Tweet’s author. While the data would probably be the Tweet ID.

Note	Publishing an event to the feeds of N users is roughly a O(N * log(N)) operation

2.2. Consuming Events (Reading / Rendering the Feed)

You can fetch the chronologically ordered events for a particular user, using:

Methods on the activity such as paginate, fetch.

Reading feed for one user (or one type of user) is a O(1) operation

For each activity (user) you can fetch the total_count and the unread_count — the number of total and new items in the feed, where unread_count is computed since the user last reset their read status.

Note: total_count can never exceed the maximum size of the feed that you configured. The default is 1000 items.

The last_read timestamp can be automatically reset when the user is shown the feed via paginate method (whether or not its reset is controlled via a method argument).

2.3. Modifying User’s Feed

For any given user, you can:

Wipe their feed with wipe

Selectively remove items from the feed with delete_if.

For instance, if a user un-follows someone they shouldn’t see their events anymore, so you’d have to call delete_if and remove any events published by the unfollowed user.

2.4. Aggregating Events

This is a feature planned for future versions.

Help us much appreciated, even if you are not a developer, but have a clear idea about how it should work.

3. Commercial & Enterprise Support

Commercial Support plans are available for SimpleFeed through author’s ReinventONE Inc consulting company. Please reach out to kig AT reinvent.one for more information.

4. Usage

4.1. Example

Please read the additional documentation, including the examples, on the project’s Github Wiki.

Below is a screen shot of an actual activity feed powered by this library.

4.2. Providers

A key concept to understanding SimpleFeed gem, is that of a provider, which is effectively a persistence implementation for the events belonging to each user.

One providers are supplied with this gem: the production-ready :redis provider, which uses the sorted set Redis data type to store and fetch the events, scored by time (but not necessarily).

You initialize a provider by using the SimpleFeed.provider([Symbol]) method.

4.3. Configuration

Below we configure a feed called :newsfeed, which in this example will be populated with the various events coming from the followers.

require 'simplefeed'

# Let's define a Redis-based feed, and wrap Redis in a in a ConnectionPool.

SimpleFeed.define(:newsfeed) do |f|
  f.provider   = SimpleFeed.provider(:redis,
                                      redis: -> { ::Redis.new },
                                      pool_size: 10)
  f.per_page   = 50     # default page size
  f.batch_size = 10     # default batch size
  f.namespace  = 'nf'   # only needed if you use the same redis for more than one feed
end

After the feed is defined, the gem creates a similarly named method under the SimpleFeed namespace to access the feed. For example, given a name such as :newsfeed the following are all valid ways of accessing the feed:

SimpleFeed.newsfeed

SimpleFeed.get(:newsfeed)

You can also get a full list of currently defined feeds with SimpleFeed.feed_names method.

4.4. Reading from and writing to the feed

For the impatient, here is a quick way to get started with the SimpleFeed.

# Let's use the feed we defined earlier and create activity for all followers of the current user
publish_activity = SimpleFeed.newsfeed.activity(@current_user.followers.map(&:id))

# Store directly the value and the optional time stamp
publish_activity.store(value: 'hello', at: Time.now)
# => true  # indicates that value 'hello' was not yet in the feed (all events must be unique)

# Or, using the event form:
publish_activity.store(event: SimpleFeed::Event.new('good bye', Time.now))
# => true

As we’ve added the two events for these users, we can now read them back, sorted by the time and paginated:

# Let's grab the first follower
user_activity = SimpleFeed.newsfeed.activity(@current_user.followers.first.id)

# Now we can paginate the events, while resetting this user's last-read timestamp:
user_activity.paginate(page: 1, reset_last_read: true)
# [
#     [0] #<SimpleFeed::Event: value=hello, at=1480475294.0579991>,
#     [1] #<SimpleFeed::Event: value=good bye, at=1480472342.8979871>,
# ]

Important

Note that we stored the activity by passing an array of users, but read the activity for just one user. This is how you’d use SimpleFeed most of the time, with the exception of the alternative mapping described below.

4.5. User IDs

In the previous section you saw the examples of publishing events to many feeds, and then reading the activity for a given user.

SimpleFeed supports user IDs that are either numeric (integer) or string-based (eg, UUID). Numeric IDs are best for simplest cases, and are the most compact. String keys offer the most flexibility.

4.5.1. Activity Keys

In the next section we’ll talk about generating keys from user_ids. We mean — Redis Hash keys that uniquely map a user (or a set of users) to the activity feed they should see.

There are up to two keys that are computed depending on the situation:

data_key is used to store the actual feed events

meta_key is used to store user’s last_read status

4.5.2. Partitioning Schema

Note	This feature is only available in SimpleFeed Version 3+.

You can take advantage of string user IDs for situations where your feed requires keys to be composite for instance. Just remember that SimpleFeed does not care about what’s in your user ID, and even what you call "a user". It’s convenient to think of the activities in terms of users, because typically each user has a unique feed that only they see.

But you can just as easily use zip code as the unique activity ID, and create one feed of events per geographical location, that all folks living in that zip code share. But what about other countries?

Now you use partitioning scheme: make the "user_id" argument a combination iso_country_code.postal_code, eg for San Francisco, you’d use us.94107, but for Australia you could use, eg au.3148.

4.5.3. Relationship between an Activity and a User

One to One

In the most common case, you will have one activity per user.

For instance, in the Twitter example, each Twitter user has a unique tweeter feed that only they see.

The events are published when someone posts a tweet, to the array of all users that follow the Tweet author.

One to Many

However, SimpleFeed supports one additional use-case, where you might have one activity shared among many users.

Imagine a service that notifies residents of important announcements based on user’s zip code of residence.

We want this feed to work as follows:

All users that share a zip-code should see the same exact feed.

However, all users should never share the individual’s last_read status: so if two people read the same activity from the same zip code, their unread_count should change independently.

In terms of the activity keys, this means:

data_key should be based on the zip-code of each user, and be one to many with users.

meta_key should be based on the user ID as we want it to be 1-1 with users.

To support this use-case, SimpleFeed supports two optional transformer lambdas that can be applied to each user object when computing their activity feed hash key:

SimpleFeed.define(:zipcode_alerts) do |f|
  f.provider   = SimpleFeed.provider(:redis, redis: -> { ::Redis.new }, pool_size: 10)
  f.namespace  = 'zc'
  f.data_key_transformer = ->(user) { user.zip_code }  # actual feed data is stored once per zip code
  f.meta_key_transformer = ->(user) { user.id }        # last_read status is stored once per user
end

When you publish events into this feed, you would need to provide User objects that all respond to .zip_code method (based on the above configuration). Since the data is only defined by Zip Code, you probably don’t want to be publishing it via a giant array of users. Most likely, you’ll want to publish event based on the zip code, and consume them based on the user ID.

To support this user-case, let’s modify our transformer lambda (only the data one) as follows — so that it can support both the consuming read by a user case, and the publishing a feed by zip code case:

Alternatively, you could do something like this:

  f.data_key_transformer = ->(entity) do
    case entity
      when User
        entity.zip_code.to_i
      when String # UUIDs
        User.find(entity)&.zip_code.to_i
      when ZipCode, Numeric
        entity.to_i
      else
        raise ArgumentError, "Invalid type #{entity.class.name}"
    end
  end

Just make sure that your users always have .zip_code defined, and that ZipCode.new(94107).to_i returns exactly the same thing as @user.zip_code.to_i or your users won’t see the feeds they are supposed to see.

4.6. The Two Forms of the Feed API

The feed API is offered in two forms:

single-user form, and

a batch (multi-user) form.

The method names and signatures are the same. The only difference is in what the methods return:

In the single user case, the return of, say, #total_count is an Integer value representing the total count for this user.

In the multi-user case, the return is a SimpleFeed::Response instance, that can be thought of as a Hash, that has the user IDs as the keys, and return results for each user as a value.

Please see further below the details about the Batch API.

Single-User API

In the examples below we show responses based on a single-user usage. As previously mentioned, the multi-user usage is the same, except what the response values are, and is discussed further down below.

Let’s take a look at a ruby session, which demonstrates return values of the feed operations for a single user:

require 'simplefeed'

# Define the feed using Redis provider, which uses
# SortedSet to keep user's events sorted.
SimpleFeed.define(:followers) do |f|
  f.provider = SimpleFeed.provider(:redis)
  f.per_page = 50
  f.per_page = 2
end

# Let's get the Activity instance that wraps this
activity = SimpleFeed.followers.activity(user_id)         # => [... complex object removed for brevity ]

# let's clear out this feed to ensure it's empty
activity.wipe                                             # => true

# Let's verify that the counts for this feed are at zero
activity.total_count                                      # => 0
activity.unread_count                                     # => 0

# Store some events
activity.store(value: 'hello')                            # => true
activity.store(value: 'goodbye', at: Time.now - 20)       # => true
activity.unread_count                                     # => 2

# Now we can paginate the events, while resetting this user's last-read timestamp:
activity.paginate(page: 1, reset_last_read: true)
# [
#     [0] #<SimpleFeed::Event: value=good bye, at=1480475294.0579991>,
#     [1] #<SimpleFeed::Event: value=hello, at=1480475294.057138>
# ]
# Now the unread_count should return 0 since the user just "viewed" the feed.
activity.unread_count                                     # => 0
activity.delete(value: 'hello')                           # => true
# the next method yields to a passed in block for each event in the user's feed, and deletes
# all events for which the block returns true. The return of this call is the
# array of all events that have been deleted for this user.
activity.delete_if do |event, user_id|
  event.value =~ /good/
end
# => [
#     [0] #<SimpleFeed::Event: value=good bye, at=1480475294.0579991>
# ]
activity.total_count                                      # => 0

You can fetch all items (optionally filtered by time) in the feed using #fetch, #paginate and reset the last_read timestamp by passing the reset_last_read: true as a parameter.

Batch (Multi-User) API

This API should be used when dealing with an array of users (or, in the future, a Proc or an ActiveRecord relation).

There are several reasons why this API should be preferred for operations that perform a similar action across a range of users: various provider implementations can be heavily optimized for concurrency, and performance.
The Redis Provider, for example, uses a notion of pipelining to send updates for different users asynchronously and concurrently.

Multi-user operations return a SimpleFeed::Response object, which can be used as a hash (keyed on user_id) to fetch the result of a given user.

# Using the Feed API with, eg #find_in_batches
@event_producer.followers.find_in_batches do |group|

  # Convert a group to the array of IDs and get ready to store
  activity = SimpleFeed.get(:followers).activity(group.map(&:id))
  activity.store(value: "#{@event_producer.name} liked an article")

  # => [Response] { user_id1 => [Boolean], user_id2 => [Boolean]... }
  # true if the value was stored, false if it wasn't.
end

Activity Feed DSL (Domain-Specific Language)

The library offers a convenient DSL for adding feed functionality into your current scope.

To use the module, just include SimpleFeed::DSL where needed, which exports just one primary method #with_activity. You call this method and pass an activity object created for a set of users (or a single user), like so:

require 'simplefeed/dsl'
include SimpleFeed::DSL

feed = SimpleFeed.newsfeed
activity = feed.activity(current_user.id)
data_to_store = %w(France Germany England)

def report(value)
  puts value
end

with_activity(activity, countries: data_to_store) do
  # we can use countries as a variable because it was passed above in **opts
  countries.each do |country|
    # we can call #store without a receiver because the block is passed to
    # instance_eval
    store(value: country) { |result| report(result ? 'success' : 'failure') }
    # we can call #report inside the proc because it is evaluated in the
    # outside context of the #with_activity

    # now let's print a color ASCII dump of the entire feed for this user:
    color_dump
  end
  printf "Activity counts are: %d unread of %d total\n", unread_count, total_count
end

The DSL context has access to two additional methods:

#event(value, at) returns a fully constructed SimpleFeed::Event instance

#color_dump prints to STDOUT the ASCII text dump of the current user’s activities (events), as well as the counts and the last_read shown visually on the time line.

#color_dump

Below is an example output of color_dump method, which is intended for the debugging purposes.

Figure 1. #color_dump method output

5. Complete API

For completeness sake we’ll show the multi-user API responses only. For a single-user use-case the response is typically a scalar, and the input is a singular user_id, not an array of ids.

Multi-User (Batch) API

Each API call at this level expects an array of user IDs, therefore the return value is an object, SimpleFeed::Response, containing individual responses for each user, accessible via response[user_id] method.

@multi = SimpleFeed.get(:feed_name).activity(User.active.map(&:id))

@multi.store(value:, at:)
@multi.store(event:)
# => [Response] { user_id => [Boolean], ... } true if the value was stored, false if it wasn't.

@multi.delete(value:, at:)
@multi.delete(event:)
# => [Response] { user_id => [Boolean], ... } true if the value was removed, false if it didn't exist

@multi.delete_if do |event, user_id|
  # if the block returns true, the event is deleted and returned
end
# => [Response] { user_id => [deleted_event1, deleted_event2, ...], ... }

# Wipe the feed for a given user(s)
@multi.wipe
# => [Response] { user_id => [Boolean], ... } true if user activity was found and deleted, false otherwise

# Return a paginated list of all items, optionally with the total count of items
@multi.paginate(page: 1,
                per_page: @multi.feed.per_page,
                with_total: false,
                reset_last_read: false)
# => [Response] { user_id => [Array]<Event>, ... }
# Options:
#   reset_last_read: false — reset last read to Time.now (true), or the provided timestamp
#   with_total: true — returns a hash for each user_id:
#        => [Response] { user_id => { events: Array<Event>, total_count: 3 }, ... }

# Return un-paginated list of all items, optionally filtered
@multi.fetch(since: nil, reset_last_read: false)
# => [Response] { user_id => [Array]<Event>, ... }
# Options:
#   reset_last_read: false — reset last read to Time.now (true), or the provided timestamp
#   since: <timestamp> — if provided, returns all items posted since then
#   since: :last_read — if provided, returns all unread items and resets +last_read+

@multi.reset_last_read
# => [Response] { user_id => [Time] last_read, ... }

@multi.total_count
# => [Response] { user_id => [Integer, String] total_count, ... }

@multi.unread_count
# => [Response] { user_id => [Integer, String] unread_count, ... }

@multi.last_read
# => [Response] { user_id => [Time] last_read, ... }

6. Providers

As we’ve discussed above, a provider is an underlying persistence mechanism implementation.

It is the intention of this gem that:

it should be easy to write new providers

it should be easy to swap out providers

One provider is included with this gem:

6.1. `SimpleFeed::Providers::Redis::Provider`

Redis Provider is a production-ready persistence adapter that uses the sorted set Redis data type.

This provider is optimized for large writes and can use either a single Redis instance for all users of your application, or any number of Redis shards by using a Twemproxy in front of the Redis shards.

If you set environment variable REDIS_DEBUG to true and run the example (see below) you will see every operation redis performs. This could be useful in debugging an issue or submitting a bug report.

7. Running the Examples and Specs

Source code for the gem contains the examples folder with an example file that can be used to test out the providers, and see what they do under the hood.

Both the specs and the example requires a local redis instance to be available.

To run it, checkout the source of the library, and then:

git clone https://github.com/kigster/simple-feed.git
cd simple-feed

# on OSX with HomeBrew:
brew install redis
brew services start redis

# check that your redis is up:
redis-cli info

# install bundler and other dependencies
gem install bundler --version 2.1.4
bundle install
bundle exec rspec  # make sure tests are passing

# run the example:
ruby examples/redis_provider_example.rb

The above command will help you download, setup all dependencies, and run the examples for a single user:

Figure 2. Running Redis Example in a Terminal

If you set REDIS_DEBUG variable prior to running the example, you will be able to see every single Redis command executed as the example works its way through. Below is a sample output:

Figure 3. Running Redis Example with REDIS_DEBUG set

7.1. Generating Ruby API Documentation

rake doc

This should use Yard to generate the documentation, and open your browser once it’s finished.

7.2. Installation

Add this line to your application’s Gemfile:

gem 'simple-feed'

And then execute:

$ bundle

Or install it yourself as:

$ gem install simple-feed

7.3. Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

7.4. Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/kigster/simple-feed

7.5. License

The gem is available as open source under the terms of the MIT License.

FOSSA Scan Status

7.6. Acknowledgements

This project is conceived and sponsored by Simbi, Inc..

Author’s personal experience at Wanelo, Inc. has served as an inspiration.

Author: kigster
Source code: https://github.com/kigster/simple-feed
License: MIT license

#ruby #ruby-on-rails

Dejuan Runolfsdottir

1615954380

How to Apply Texture to Text in Photoshop | Photoshop Tutorial

The techniques you’ll learn here would apply to almost any font, as well as shapes. So grab your favorite text, and let’s start designing.

Here’s what you’ll learn how to do in this video:

00:28 - Place down the text
00:42 - Copy a texture into the document
01:10 - Apply a mask to the texture
01:52 - Apply layer styles
02:19 - Add additional textures
03:18 - Customize a template

#photoshop #developer

How To Apply a Cinematic Color Grade in Photoshop

What's New

Usage

1. Setting the splash screen

2. Run the package

3. Set up app initialization (optional)

4. Support the package (optional)

Android 12+ Support

Flavor Support

Pre-requirements

Android setup

iOS setup

FAQs

I got the error "A splash screen was provided to Flutter, but this is deprecated."

Are animations/lottie/GIF images supported?

I got the error AAPT: error: style attribute 'android:attr/windowSplashScreenBackground' not found

I see a flash of the wrong splash screen on iOS

I see a white screen between splash screen and app

Can I base light/dark mode on app settings?

How it works

Android

iOS

Web

Acknowledgments

Bugs or Requests

Use this package as a library

Depend on it

Import it

Download Details:

Initializing Spark

SparkContext

Inspect SparkContext

Configuration

Using the Shell

Loading Data

Parallelized Collections

External Data

Retrieving RDD Information

Basic Information

Summary

Applying Functions

Selecting Data

Iterating

Reshaping Data

Mathematical Operations

Sort

Repartitioning

Saving

Stopping SparkContext

Execution

SimpleFeed

1. Scalable, Easy to Use Activity Feed Implementation.

1.1. Build & Gem Status

1.2. Test Coverage Map

2. Features

2.1. Publishing Events

2.2. Consuming Events (Reading / Rendering the Feed)

2.3. Modifying User’s Feed

2.4. Aggregating Events

3. Commercial & Enterprise Support

4. Usage

4.1. Example

4.2. Providers

4.3. Configuration

4.4. Reading from and writing to the feed

4.5. User IDs

4.5.1. Activity Keys

4.5.2. Partitioning Schema

4.5.3. Relationship between an Activity and a User

4.6. The Two Forms of the Feed API

5. Complete API

Multi-User (Batch) API

6. Providers

6.1. SimpleFeed::Providers::Redis::Provider

7. Running the Examples and Specs

7.1. Generating Ruby API Documentation

7.2. Installation

7.3. Development

7.4. Contributing

7.5. License

6.1. `SimpleFeed::Providers::Redis::Provider`