Tutorial by Examples: ti

pip doesn't current contain a flag to allow a user to update all outdated packages in one shot. However, this can be accomplished by piping commands together in a Linux environment: pip list --outdated --local | grep -v '^\-e' | cut -d = -f 1 | xargs -n1 pip install -U This command takes all pa...

pip doesn't current contain a flag to allow a user to update all outdated packages in one shot. However, this can be accomplished by piping commands together in a Windows environment: for /F "delims= " %i in ('pip list --outdated --local') do pip install -U %i This command takes all pa...

Class composition allows explicit relations between objects. In this example, people live in cities that belong to countries. Composition allows people to access the number of all people living in their country: class Country(object): def __init__(self): self.cities=[] ...

The steps of overload resolution are: Find candidate functions via name lookup. Unqualified calls will perform both regular unqualified lookup as well as argument-dependent lookup (if applicable). Filter the set of candidate functions to a set of viable functions. A viable function for whi...

In the timeline of any DisplayObject that is attached as a descendant of the display tree, you can utilise the root property. This property points to the main timeline in the case of no custom document class, or the document class if you do define one. Because root is typed DisplayObject, the compi...

Enums are iterable: class Color(Enum): red = 1 green = 2 blue = 3 [c for c in Color] # [<Color.red: 1>, <Color.green: 2>, <Color.blue: 3>]

<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"> <circle r="30" cx="100" cy="100" fill="#ff0000" stroke="#00ff00" /> <rect x="200" y="200" width="50&...

To search for a string inside a string, there are several functions: indexOf( searchString ) and lastIndexOf( searchString ) indexOf() will return the index of the first occurrence of searchString in the string. If searchString is not found, then -1 is returned. var string = "Hello, World!&q...

Sometimes it is useful to have multiple validations use one condition. It can be easily achieved using with_options. class User < ApplicationRecord with_options if: :is_admin? do |admin| admin.validates :password, length: { minimum: 10 } admin.validates :email, presence: true end...

This type of association allows an ActiveRecord model to belong to more than one kind of model record. Common example: class Human < ActiveRecord::Base has_one :address, :as => :addressable end class Company < ActiveRecord::Base has_one :address, :as => :addressable end cl...

While RODBC is restricted to Windows computers with compatible architecture between R and any target RDMS, one of its key flexibilities is to work with Excel files as if they were SQL databases. require(RODBC) con = odbcConnectExcel("myfile.xlsx") # open a connection to the Excel file s...

Log4j gives you posibility to log data into console and file at same time. Create a log4j.properties file and put inside this basic configuration: # Root logger option log4j.rootLogger=DEBUG, stdout, file # Redirect log messages to console log4j.appender.stdout=org.apache.log4j.ConsoleAppende...

If the help function is called in the console without any arguments, Python presents an interactive help console, where you can find out about Python modules, symbols, keywords and more. >>> help() Welcome to Python 3.4's help utility! If this is your first time using Python, you sho...

The Python console adds a new function, help, which can be used to get information about a function or object. For a function, help prints its signature (arguments) and its docstring, if the function has one. >>> help(print) Help on built-in function print in module builtins: print(.....

Install the SDK Download & unzip the SDK Make sure you are using the latest version of Xcode (7.0+) and targeting iOS 7.0 or highe Download SDK Add the SDKs to your app Drag the Parse.framework and Bolts.framework you downloaded into your Xcode project folder target. Make sure th...

Sometimes you need to keep a linear (non-branching) history of your code commits. If you are working on a branch for a while, this can be tricky if you have to do a regular git pull since that will record a merge with upstream. [alias] up = pull --rebase This will update with your upstream so...

You can use the star * when writing a function to collect all positional (ie. unnamed) arguments in a tuple: def print_args(farg, *args): print("formal arg: %s" % farg) for arg in args: print("another positional arg: %s" % arg) Calling method: print_args(1, &...

You can define a function that takes an arbitrary number of keyword (named) arguments by using the double star ** before a parameter name: def print_kwargs(**kwargs): print(kwargs) When calling the method, Python will construct a dictionary of all keyword arguments and make it available in ...

A common use case for *args in a function definition is to delegate processing to either a wrapped or inherited function. A typical example might be in a class's __init__ method class A(object): def __init__(self, b, c): self.y = b self.z = c class B(A): def __init__(...

You can use a dictionary to assign values to the function's parameters; using parameters name as keys in the dictionary and the value of these arguments bound to each key: def test_func(arg1, arg2, arg3): # Usual function with three arguments print("arg1: %s" % arg1) print("a...