Tutorial by Examples: r

Installation or Setup

Detailed instructions on getting push-notification set up or installed.

push-notification • Getting started with push-notification

`Could not deduce (Fractional Int) ...`

The error message in the title is a common beginner mistake. Let's see how it arises and how to fix it. Suppose we need to compute the average value of a list of numbers; the following declaration would seem to do it, but it wouldn't compile: averageOfList ll = sum ll / length ll The problem is...

Haskell Language • Arithmetic

Get the HTML content of CKEditor

Create a file ckeditor-content.html with the following content: <!DOCTYPE html> <html> <head> <title>CKEditor Get Content Demo!</title> </head> <body> <script src="//cdn.ckeditor.com/4.6.1/basic/ckeditor.js"></script> ...

ckeditor • Getting started with ckeditor

Enumerating through keys and Key-Value Pairs

Enumerating through Keys foreach ($key in $var1.Keys) { $value = $var1[$key] # or $value = $var1.$key } Enumerating through Key-Value Pairs foreach ($keyvaluepair in $var1.GetEnumerator()) { $key1 = $_.Key1 $val1 = $_.Val1 }

PowerShell • HashTables

Dual-purpose modules (refinements or global patches)

It's a good practice to scope patches using Refinements, but sometimes it's nice to load it globally (for example in development, or testing). Say for example you want to start a console, require your library, and then have the patched methods available in the global scope. You couldn't do this wit...

Ruby Language • Refinements

Dynamic refinements

Refinements have special limitations. refine can only be used in a module scope, but can be programmed using send :refine. using is more limited. It can only be called in a class/module definition. Still, it can accept a variable pointing to a module, and can be invoked in a loop. An example show...

Ruby Language • Refinements

Plot live data from pipe with matplotlib

This can be usefull when you want to visualize incoming data in real-time. This data could, for example, come from a microcontroller that is continuously sampling an analog signal. In this example we will get our data from a named pipe (also known as a fifo). For this example, the data in the pipe ...

matplotlib • Animations and interactive plotting

Assigning function to a variable

struct Mathematics { internal func performOperation(inputArray: [Int], operation: (Int)-> Int)-> [Int] { var processedArray = [Int]() for item in inputArray { processedArray.append(operation(item)) } retur...

Swift Language • Function as first class citizens in Swift

Passing function as an argument to another function, thus creating a Higher-Order Function

func multiply2(item: Int)-> Int { return (item + 2) } let multiply2ToMe = multiply2 // passing the function directly to the function as param print(math.performOperation(inputArray: arrayToBeProcessed, operation: multiply2ToMe)) Output: [3, 5, 7, 9, 11, 13, 10, 8, 6, 4, 102] ...

Swift Language • Function as first class citizens in Swift

Function as return type from another function

// function as return type print(math.performComplexOperation(valueOne: 4)(5)) Output: 9

Swift Language • Function as first class citizens in Swift

Master Detail Navigation

The code below shows how to perform asynchronous navigation when the app is in a MasterDetailPage context. public async Task NavigateMasterDetail(Page page) { if (page == null) { return; } var masterDetail = App.Current.MainPage as Mas...

Xamarin.Forms • Navigation in Xamarin.Forms

Taking screenshots

The following will produce a PNG image in the current directory of the loaded page. chrome --headless --screenshot https://stackoverflow.com

google-chrome • Headless browsing

Interacting with documents

Using the --remote-debugging-port to expose a debugger accessible over HTTP is one way appliances can connect and interact with the document using the Chrome Debugging Protocol. chrome --headless --remote-debugging-port=9222 https://stackoverflow.com You can then navigate to http://localhost:9222 ...

google-chrome • Headless browsing

Responsive image using the srcset attribute

Using srcset with sizes <img sizes="(min-width: 1200px) 580px, (min-width: 640px) 48vw, 98vw" srcset="img/hello-300.jpg 300w, img/hello-600.jpg 600w, img/hello-900.jpg 900w, img/hello-1200.jpg 1200w" src="img/hello-900.jpg&quo...

HTML • Images

Formatting data types to String and vise versa

Data types to string formatting Data types like int, float, double, long, boolean can be formatted to string using String.valueOf(). String.valueOf(1); //Output -> "1" String.valueOf(1.0); //Output -> "1.0" String.valueOf(1.2345); //Output -> "1.2345" Stri...

Android • Formatting Strings

Installation or Setup

Detailed instructions on getting sharepoint-2013 set up or installed.

sharepoint-2013 • Getting started with sharepoint-2013

Accessing query string

The query string is the part of a request following the URL, preceded by a ? mark. Example: https://encrypted.google.com/search?hl=en&q=stack%20overflow For this example, we are making a simple echo webserver that echos back everything submitted to it via the echo field in GET requests. Examp...

Flask • Accessing request data

Combined form and query string

Flask also allows access to a CombinedMultiDict that gives access to both the request.form and request.args attributes under one variable. This example pulls data from a form field name submitted along with the echo field in the query string. Flask Example: from flask import Flask, request app...

Flask • Accessing request data

Accessing form fields

You can access the form data submitted via a POST or PUT request in Flask via the request.form attribute. from flask import Flask, request app = Flask(import_name=__name__) @app.route("/echo", methods=["POST"]) def echo(): name = request.form.get("name"...

Flask • Accessing request data

Non-escaping closure

In Swift 1 and 2, closure parameters were escaping by default. If you knew your closure wouldn’t escape the function body, you could mark the parameter with the @noescape attribute. In Swift 3, it’s the other way around: closure parameters are non-escaping by default. If you intend for it to escape...

Swift Language • Blocks