Tutorial by Examples: p

The emptiness of a list is associated to the boolean False, so you don't have to check len(lst) == 0, but just lst or not lst lst = [] if not lst: print("list is empty") # Output: list is empty

Assuming that bar is an alias for someCommand -flag1. Type bar on the command line and then press Ctrl+alt+e you'll get someCommand -flag1 where bar was standing.

This example assumes you have already installed Java and Gradle. Use the following project structure: src/ main/ java/ com/ example/ Application.java build.gradle build.gradle is your build script for Gradle build system with the following content: buildscri...

You should implement SFSafariViewControllerDelegate so that your class is notified when the user hits the Done button on the SafariViewController and you can dismiss it as well. First declare your class to implement the protocol. class MyClass: SFSafariViewControllerDelegate { } Implement th...

Don't forget to import the necessary framework first. import SafariServices //Objective-C @import SafariServices; Instantiate a SafariViewController instance. let safariVC = SFSafariViewController(URL: URL(string: "your_url")!) //Objective-C @import SafariServices; NSURL *URL = [...

The function map() from the package maps provides a simple starting point for creating maps with R. A basic world map can be drawn as follows: require(maps) map() The color of the outline can be changed by setting the color parameter, col, to either the character name or hex value of a color...

if /hay/ =~ 'haystack' puts "There is hay in the word haystack" end Note: The order is significant. Though 'haystack' =~ /hay/ is in most cases an equivalent, side effects might differ: Strings captured from named capture groups are assigned to local variables only when Regexp#=~...

Say you have a library website, and you want to have a custom post type named Books. It can be registered as function create_bookposttype() { $args = array( 'public' => true, 'labels' => array( 'name' => __( 'Books' ), 'singular_name' => ...

There are 16 fundamental data types, or classes, in MATLAB. Each of these classes is in the form of a matrix or array. With the exception of function handles, this matrix or array is a minimum of 0-by-0 in size and can grow to an n-dimensional array of any size. A function handle is always scalar (1...

A factory decreases coupling between code that needs to create objects from object creation code. Object creation is not made explicitly by calling a class constructor but by calling some function that creates the object on behalf the caller. A simple Java example is the following one: interface Ca...

A basic plot is created by calling plot(). Here we use the built-in cars data frame that contains the speed of cars and the distances taken to stop in the 1920s. (To find out more about the dataset, use help(cars)). plot(x = cars$speed, y = cars$dist, pch = 1, col = 1, main = "Distance ...

matplot is useful for quickly plotting multiple sets of observations from the same object, particularly from a matrix, on the same graph. Here is an example of a matrix containing four sets of random draws, each with a different mean. xmat <- cbind(rnorm(100, -3), rnorm(100, -1), rnorm(100, 1),...

The following program says hello to the user. It takes one positional argument, the name of the user, and can also be told the greeting. import argparse parser = argparse.ArgumentParser() parser.add_argument('name', help='name of user' ) parser.add_argument('-g', '--greeting', ...

To join two or more path components together, firstly import os module of python and then use following: import os os.path.join('a', 'b', 'c') The advantage of using os.path is that it allows code to remain compatible over all operating systems, as this uses the separator appropriate for the pl...

Use os.path.abspath: >>> os.getcwd() '/Users/csaftoiu/tmp' >>> os.path.abspath('foo') '/Users/csaftoiu/tmp/foo' >>> os.path.abspath('../foo') '/Users/csaftoiu/foo' >>> os.path.abspath('/foo') '/foo'

To split one component off of the path: >>> p = os.path.join(os.getcwd(), 'foo.txt') >>> p '/Users/csaftoiu/tmp/foo.txt' >>> os.path.dirname(p) '/Users/csaftoiu/tmp' >>> os.path.basename(p) 'foo.txt' >>> os.path.split(os.getcwd()) ('/Users/csafto...

docopt turns command-line argument parsing on its head. Instead of parsing the arguments, you just write the usage string for your program, and docopt parses the usage string and uses it to extract the command line arguments. """ Usage: script_name.py [-a] [-b] <path> ...

Comparing sets In R, a vector may contain duplicated elements: v = "A" w = c("A", "A") However, a set contains only one copy of each element. R treats a vector like a set by taking only its distinct elements, so the two vectors above are regarded as the same: set...

The %in% operator compares a vector with a set. v = "A" w = c("A", "A") w %in% v # TRUE TRUE v %in% w # TRUE Each element on the left is treated individually and tested for membership in the set associated with the vector on the right (consisting of all its...

To find every vector of the form (x, y) where x is drawn from vector X and y from Y, we use expand.grid: X = c(1, 1, 2) Y = c(4, 5) expand.grid(X, Y) # Var1 Var2 # 1 1 4 # 2 1 4 # 3 2 4 # 4 1 5 # 5 1 5 # 6 2 5 The result is a data.frame with one...