Tutorial by Examples: f

for loops iterate over a collection of items, such as list or dict, and run a block of code with each element from the collection. for i in [0, 1, 2, 3, 4]: print(i) The above for loop iterates over a list of numbers. Each iteration sets the value of i to the next element of the list. So f...

import random shuffle() You can use random.shuffle() to mix up/randomize the items in a mutable and indexable sequence. For example a list: laughs = ["Hi", "Ho", "He"] random.shuffle(laughs) # Shuffles in-place! Don't do: laughs = random.shuffle(laughs) p...

import random randint() Returns a random integer between x and y (inclusive): random.randint(x, y) For example getting a random number between 1 and 8: random.randint(1, 8) # Out: 8 randrange() random.randrange has the same syntax as range and unlike random.randint, the last value is no...

There are several flags you can specify to alter the RegEx behaviour. Flags may be appended to the end of a regex literal, such as specifying gi in /test/gi, or they may be specified as the second argument to the RegExp constructor, as in new RegExp('test', 'gi'). g - Global. Finds all matches inst...

var re = /[a-z]+/; if (re.test("foo")) { console.log("Match exists."); } The test method performs a search to see if a regular expression matches a string. The regular expression [a-z]+ will search for one or more lowercase letters. Since the pattern matches the string,...

Assuming you set the upstream (as in the "setting an upstream repository") git fetch remote-name git merge remote-name/branch-name The pull command combines a fetch and a merge. git pull The pull with --rebase flag command combines a fetch and a rebase instead of merge. git pull ...

To stage a file for committing, run git add <filename>

git add -A 2.0 git add . In version 2.x, git add . will stage all changes to files in the current directory and all its subdirectories. However, in 1.x it will only stage new and modified files, not deleted files. Use git add -A, or its equivalent command git add --all, to stage all ch...

You can make Git ignore certain files and directories — that is, exclude them from being tracked by Git — by creating one or more .gitignore files in your repository. In software projects, .gitignore typically contains a listing of files and/or directories that are generated during the build proces...

import java.awt.Image; import javax.imageio.ImageIO; ... try { Image img = ImageIO.read(new File("~/Desktop/cat.png")); } catch (IOException e) { e.printStackTrace(); }

Optionals are a generic enum type that acts as a wrapper. This wrapper allows a variable to have one of two states: the value of the user-defined type or nil, which represents the absence of a value. This ability is particularly important in Swift because one of the stated design objectives of the ...

Instead of importing the complete module you can import only specified names: from random import randint # Syntax "from MODULENAME import NAME1[, NAME2[, ...]]" print(randint(1, 10)) # Out: 5 from random is needed, because the python interpreter has to know from which resource it...

#include <stdio.h> /* increment: take number, increment it by one, and return it */ int increment(int i) { printf("increment %d by 1\n", i); return i + 1; } /* decrement: take number, decrement it by one, and return it */ int decrement(int i) { printf("...

#include <stdio.h> enum Op { ADD = '+', SUB = '-', }; /* add: add a and b, return result */ int add(int a, int b) { return a + b; } /* sub: subtract b from a, return result */ int sub(int a, int b) { return a - b; } /* getmath: return the appropriate m...

from module_name import * for example: from math import * sqrt(2) # instead of math.sqrt(2) ceil(2.7) # instead of math.ceil(2.7) This will import all names defined in the math module into the global namespace, other than names that begin with an underscore (which indicates that the wri...

min(7,2,1,5) # Output: 1 max(7,2,1,5) # Output: 7

You can't pass an empty sequence into max or min: min([]) ValueError: min() arg is an empty sequence However, with Python 3, you can pass in the keyword argument default with a value that will be returned if the sequence is empty, instead of raising an exception: max([], default=42) ...

Arrays of strings can be created using ruby's percent string syntax: array = %w(one two three four) This is functionally equivalent to defining the array as: array = ['one', 'two', 'three', 'four'] Instead of %w() you may use other matching pairs of delimiters: %w{...}, %w[...] or %w<...&...

2.0 array = %i(one two three four) Creates the array [:one, :two, :three, :four]. Instead of %i(...), you may use %i{...} or %i[...] or %i!...! Additionally, if you want to use interpolation, you can do this with %I. 2.0 a = 'hello' b = 'goodbye' array_one = %I(#{a} #{b} world) array_tw...

The groupingBy(classifier, downstream) collector allows the collection of Stream elements into a Map by classifying each element in a group and performing a downstream operation on the elements classified in the same group. A classic example of this principle is to use a Map to count the occurrence...