Tutorial by Examples: ad

drop shadow

JSFiddle: https://jsfiddle.net/UnsungHero97/80qod7aL/ HTML <div class="box_shadow"></div> CSS .box_shadow { -webkit-box-shadow: 0px 0px 10px -1px #444444; -moz-box-shadow: 0px 0px 10px -1px #444444; box-shadow: 0px 0px 10px -1px #444444; }

CSS • box-shadow

inner drop shadow

HTML <div class="box_shadow"></div> CSS .box_shadow { background-color: #1C90F3; width: 200px; height: 100px; margin: 50px; -webkit-box-shadow: inset 0px 0px 10px 0px #444444; -moz-box-shadow: inset 0px 0px 10px 0px #444444; box-shadow: inse...

CSS • box-shadow

bottom-only drop shadow using a pseudo-element

JSFiddle: https://jsfiddle.net/UnsungHero97/80qod7aL/2/ HTML <div class="box_shadow"></div> CSS .box_shadow { background-color: #1C90F3; width: 200px; height: 100px; margin: 50px; } .box_shadow:after { content: ""; width: 190px; height: ...

CSS • box-shadow

Matching leading/trailing whitespace

Trailing spaces \s*$: This will match any (*) whitespace (\s) at the end ($) of the text Leading spaces ^\s*: This will match any (*) whitespace (\s) at the beginning (^) of the text Remarks \s is a common metacharacter for several RegExp engines, and is meant to capture whitespace characters (...

Regular Expressions • Matching Simple Patterns

Upgrade Packages

Running $ pip install --upgrade SomePackage will upgrade package SomePackage and all its dependencies. Also, pip automatically removes older version of the package before upgrade. To upgrade pip itself, do $ pip install --upgrade pip on Unix or $ python -m pip install --upgrade pip on ...

Python Language • pip: PyPI Package Manager

multiple shadows

JSFiddle: https://jsfiddle.net/UnsungHero97/80qod7aL/5/ HTML <div class="box_shadow"></div> CSS .box_shadow { width: 100px; height: 100px; margin: 100px; box-shadow: -52px -52px 0px 0px #f65314, 52px -52px 0px 0px #7cbb00, -52px 52px 0px 0px #00...

CSS • box-shadow

Read a file between a range of lines

So let's suppose you want to iterate only between some specific lines of a file You can make use of itertools for that import itertools with open('myfile.txt', 'r') as f: for line in itertools.islice(f, 12, 30): # do something here This will read through the lines 13 to 20 as i...

Python Language • Files & Folders I/O

Iterating over a directory and filter by file extension

public void iterateAndFilter() throws IOException { Path dir = Paths.get("C:/foo/bar"); PathMatcher imageFileMatcher = FileSystems.getDefault().getPathMatcher( "regex:.*(?i:jpg|jpeg|png|gif|bmp|jpe|jfif)"); try (Direc...

Java Language • File I/O

Output JSON instead of HTML

class UsersController < ApplicationController def index hashmap_or_array = [{ name: "foo", email: "[email protected]" }] respond_to do |format| format.html { render html: "Hello World" } format.json { render json: hashmap_or_array } en...

Ruby on Rails • ActionController

Additional RESTful actions

resources :photos do member do get 'preview' end collection do get 'dashboard' end end This creates the following routes in addition to default 7 RESTful routes: get '/photos/:id/preview', to: 'photos#preview' get '/photos/dashboards', to: '...

Ruby on Rails • Routing

Filenames and autoloading

Rails files - and Ruby files in general - should be named with lower_snake_case filenames. E.g. app/controllers/application_controller.rb is the file that contains the ApplicationController class definition. Note that while PascalCase is used for class and module names, the files in which they r...

Ruby on Rails • Naming Conventions

Use requestAnimationFrame to fade in element

View jsFiddle: https://jsfiddle.net/HimmatChahal/jb5trg67/ Copy + Pasteable code below: <html> <body> <h1>This will fade in at 60 frames per second (or as close to possible as your hardware allows)</h1> <script> // Fad...

JavaScript • requestAnimationFrame

Reading or writing through a null pointer

int *ptr = nullptr; *ptr = 1; // Undefined behavior This is undefined behavior, because a null pointer does not point to any valid object, so there is no object at *ptr to write to. Although this most often causes a segmentation fault, it is undefined and anything can happen.

C++ • Undefined Behavior

Spreadsheet to dict of DataFrames

with pd.ExcelFile('path_to_file.xls) as xl: d = {sheet_name: xl.parse(sheet_name) for sheet_name in xl.sheet_names}

pandas • Pandas IO tools (reading and saving data sets)

Read a specific sheet

pd.read_excel('path_to_file.xls', sheetname='Sheet1') There are many parsing options for read_excel (similar to the options in read_csv. pd.read_excel('path_to_file.xls', sheetname='Sheet1', header=[0, 1, 2], skiprows=3, index_col=0) # etc.

pandas • Pandas IO tools (reading and saving data sets)

Sorting sequence containers by overloaded less operator

If no ordering function is passed, std::sort will order the elements by calling operator< on pairs of elements, which must return a type contextually convertible to bool (or just bool). Basic types (integers, floats, pointers etc) have already build in comparison operators. We can overload this ...

C++ • Sorting

Add an unique column to a table

To add a new unique column email to users, run the following command: rails generate migration AddEmailToUsers email:string:uniq This will create the following migration: class AddEmailToUsers < ActiveRecord::Migration[5.0] def change add_column :users, :email, :string add_index...

Ruby on Rails • ActiveRecord Migrations

Adding a new column

df = pd.DataFrame({'A': [1, 2, 3], 'B': [4, 5, 6]}) print(df) # Output: # A B # 0 1 4 # 1 2 5 # 2 3 6 Directly assign df['C'] = [7, 8, 9] print(df) # Output: # A B C # 0 1 4 7 # 1 2 5 8 # 2 3 6 9 Add a constant column df['C'] = 1 print(df) # Ou...

pandas • Simple manipulation of DataFrames

Pitfall - Unnecessary use of Primitive Wrappers can lead to NullPointerExceptions

Sometimes, programmers who are new Java will use primitive types and wrappers interchangeably. This can lead to problems. Consider this example: public class MyRecord { public int a, b; public Integer c, d; } ... MyRecord record = new MyRecord(); record.a = 1; // OK ...

Java Language • Java Pitfalls - Nulls and NullPointerException

Download Image using AsyncTask in Android

This tutorial explains how to download Image using AsyncTask in Android. The example below download image while showing progress bar while during download. Understanding Android AsyncTask Async task enables you to implement MultiThreading without get Hands dirty into threads. AsyncTask enables pro...

Android • AsyncTask