Tutorial by Examples: w

The flow of execution of a Ruby block may be controlled with the break, next, and redo statements. break The break statement will exit the block immediately. Any remaining instructions in the block will be skipped, and the iteration will end: actions = %w(run jump swim exit macarena) index = 0 ...

SwiftyJSON is a Swift framework built to remove the need for optional chaining in normal JSON serialization. You can download it here: https://github.com/SwiftyJSON/SwiftyJSON Without SwiftyJSON, your code would look like this to find the name of the first book in a JSON object: if let jsonObject...

The dynamics of the Geometric Brownian Motion (GBM) are described by the following stochastic differential equation (SDE): I can use the exact solution to the SDE to generate paths that follow a GBM. Given daily parameters for a year-long simulation mu = 0.08/250; sigma = 0.25/sqrt(...

One of the things that can really boost your productivity while writing the code is effectively navigating the workspace. This also means making it comfortable for the moment. It's possible to achieve this by adjusting which areas of workspaces you see. The buttons on the top of the navigation and ...

When in a loop, the loop variable (val) in the following example is a single variable that changes value as it goes over the loop. Therefore one must do the following to actually pass each val of values to the goroutine: for val := range values { go func(val interface{}) { fmt.Println...

Template may accept both lvalue and rvalue references using forwarding reference: template <typename T> void f(T &&t); In this case, the real type of t will be deduced depending on the context: struct X { }; X x; f(x); // calls f<X&>(x) f(X()); // calls f<X>(...

<?php while ($condition): do_something(); endwhile; ?> <?php while ($condition): ?> <p>Do something in HTML</p> <?php endwhile; ?>

<?php switch ($condition): case $value: do_something(); break; default: do_something_else(); break; endswitch; ?> <?php switch ($condition): ?> <?php case $value: /* having whitespace before your cases will cause an error */ ?&g...

Interleave your y or x values with NaNs x = [1:5; 6:10]'; x(3,2) = NaN x = 1 6 2 7 3 NaN 4 9 5 10 plot(x)

Numpy installation through pypi (the default package index used by pip) generally fails on Windows computers. The easiest way to install on Windows is by using precompiled binaries. One source for precompiled wheels of many packages is Christopher Gohkle's site. Choose a version according to your ...

See how to compile this code in Initialize and build import Html main = Html.text "Hello World!"

Django uses migrations to propagate changes you make to your models to your database. Most of the time django can generate them for you. To create a migration, run: $ django-admin makemigrations <app_name> This will create a migration file in the migration submodule of app_name. The first...

m := make(map[string][]int) Accessing a non-existent key will return a nil slice as a value. Since nil slices act like zero length slices when used with append or other built-in functions you do not normally need to check to see if a key exists: // m["key1"] == nil && len(m[&qu...

To change the default stack order positioned elements (position property set to relative, absolute or fixed), use the z-index property. The higher the z-index, the higher up in the stacking context (on the z-axis) it is placed. Example In the example below, a z-index value of 3 puts green on to...

Consider the following tough-to-vectorize for loop, which creates a vector of length len where the first element is specified (first) and each element x_i is equal to cos(x_{i-1} + 1): repeatedCosPlusOne <- function(first, len) { x <- numeric(len) x[1] <- first for (i in 2:len) { ...

If you are using the default bash prompt on Linux, you should see the name of the virtual environment at the start of your prompt. (my-project-env) user@hostname:~$ which python /home/user/my-project-env/bin/python

Given the following history, imagine you make a change that you want to squash into the commit bbb2222 A second commit: $ git log --oneline --decorate ccc3333 (HEAD -> master) A third commit bbb2222 A second commit aaa1111 A first commit 9999999 Initial commit Once you've made your change...

It is common to want two views to be side by side, centered in their superview. The common answer given on Stack Overflow is to embed these two views in a UIView and center the UIView. This is not necessary or recommended. From the UILayoutGuide docs: There are a number of costs associated with...

Without JSX Here's a basic example that uses React's main API to create a React element and the React DOM API to render the React element in the browser. <!DOCTYPE html> <html> <head> <meta charset="UTF-8" /> <title>Hello React!</title> ...

This code can be added to any event like a listener, button, etc. A blocking JDialog will appear and will remain until the process is complete. final JDialog loading = new JDialog(parentComponent); JPanel p1 = new JPanel(new BorderLayout()); p1.add(new JLabel("Please wait..."), BorderLa...