Tutorial by Examples: r

Abstract factory pattern provides a way to obtain an coherent collection of objects through a collection of factories functions. As for every pattern, coupling is reduced by abstracting the way a set of objects are created, so that the user code is unaware of the many details of the objects he needs...

Factories can be used in conjunction with Inversion of Control (IoC) libraries too. The typical use case for such a factory is when we want to create an object based on parameters that are not known until run-time (such as the current User). In these cases it can be sometimes be difficult (if no...

Enumerating dictionaries allows you to run a block of code on each dictionary key-value pair using the method enumerateKeysAndObjectsUsingBlock:(void (^)(id key, id obj, BOOL *stop))block Example: NSDictionary stockSymbolsDictionary = @{ @"AAPL":...

In [1]: import numpy as np In [2]: import pandas as pd In [3]: df = pd.DataFrame({'A': list('XYZXYZXYZX'), 'B': [1, 2, 1, 3, 1, 2, 3, 3, 1, 2], 'C': [12, 14, 11, 12, 13, 14, 16, 12, 10, 19]}) In [4]: df.groupby('A')['B'].agg({'mean': np.mean, 'standard deviatio...

Given a file file.txt with the following content: line 1 line 2 line 3 You can delete a line from file content with the d command. The pattern to match is surrounded with default / delimiter and the d command follows the pattern: sed '/line 2/d' file.txt The above command will output: l...

Fourier Transform is probably the first lesson in Digital Signal Processing, it's application is everywhere and it is a powerful tool when it comes to analyze data (in all sectors) or signals. Matlab has a set of powerful toolboxes for Fourier Transform. In this example, we will use Fourier Transfor...

If you set opacity on an element it will affect all its child elements. To set an opacity just on the background of an element you will have to use RGBA colors. Following example will have a black background with 0.6 opacity. /* Fallback for web browsers that don't support RGBa */ background-color...

Objective-C mySwitch.backgroundColor = [UIColor yellowColor]; [mySwitch setBackgroundColor: [UIColor yellowColor]]; mySwitch.backgroundColor =[UIColor colorWithRed:255/255.0 green:0/255.0 blue:0/255.0 alpha:1.0]; mySwitch.backgroundColor= [UIColor colorWithWhite: 0.5 alpha: 1.0]; mySwitch.backg...

Objective-C //for off-state mySwitch.tintColor = [UIColor blueColor]; [mySwitch setTintColor: [UIColor blueColor]]; //for on-state mySwitch.onTintColor = [UIColor cyanColor]; [mySwitch setOnTintColor: [UIColor cyanColor]]; Swift //for off-state mySwitch.tintColor = UIColor.blueColor() ...

If your project depends on the external libraries, you should first install them with opam. Assuming your dependencies are foo and bar and the main entry point of your project is foobar.ml you can then build a bytecode executable with ocamlbuild -use-ocamlfind -pkgs 'foo,bar' foobar.byte Warnin...

If your project has no external dependency and has foo.ml as its main entry point, you can compile a bytecode version with ocamlbuild foo.byte To get a native executable, run ocamlbuild foo.native

import pandas as pd import numpy as np df = pd.DataFrame({'A':[1,2,np.nan,3,np.nan], 'B':[1.2,7,3,0,8]}) df['C'] = df.A.interpolate() df['D'] = df.A.interpolate(method='spline', order=1) print (df) A B C D 0 1.0 1.2 1.0 1.000000 1 2.0 7.0 2...

Fortran 2003 introduced language features which can guarantee interoperability between C and Fortran (and to more languages by using C as an intermediary). These features are mostly accessed through the intrinsic module iso_c_binding: use, intrinsic :: iso_c_binding The intrinsic keyword here en...

The bind attribute can also be applied to derived types: geese.h struct Goose { int flock; float buoyancy; } struct Goose goose_c; geese.f90 use, intrinsic :: iso_c_binding, only : c_int, c_float type, bind(C) :: goose_t integer(c_int) :: flock real(c_float) :: buoyancy e...

In attempt to send a response asynchronously from chrome.runtime.onMessage callback we might try this wrong code: chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) { $.ajax({ url: 'https://www.google.com', method: 'GET', success: functio...

Homebrew You can install Node.js using the Homebrew package manager. Start by updating brew: brew update You may need to change permissions or paths. It's best to run this before proceeding: brew doctor Next you can install Node.js by running: brew install node Once Node.js is installe...

Detailed instructions on getting hdfs set up or installed.

Transforms hold the majority of data about an object in unity, including it's parent(s), child(s), position, rotation, and scale. It also has functions to modify each of these properties. Every GameObject has a Transform. Translating (moving) an object // Move an object 10 units in the positive ...

Encoding //Create a Base64 Encoded NSString Object NSData *nsdata = [@"iOS Developer Tips encoded in Base64" dataUsingEncoding:NSUTF8StringEncoding]; // Get NSString from NSData object in Base64 NSString *base64Encoded = [nsdata base64EncodedStringWithOptions:0]; // Print the B...

You can find the installers on Node.js download page. Normally, Node.js recommends two versions of Node, the LTS version (long term support) and the current version (latest release). If you are new to Node, just go for the LTS and then click the Macintosh Installer button to download the package. I...