Tutorial by Examples: me

Basic example of using requests and lxml to scrape some data

# For Python 2 compatibility. from __future__ import print_function import lxml.html import requests def main(): r = requests.get("https://httpbin.org") html_source = r.text root_element = lxml.html.fromstring(html_source) # Note root_element.xpath() gives a *...

Python Language • Web scraping with Python

Parameters

Controllers have access to HTTP parameters (you might know them as ?name=foo in URLs, but Ruby on Rails handle different formats too!) and output different responses based on them. There isn't a way to distinguish between GET and POST parameters, but you shouldn't do that in any case. class UsersCo...

Ruby on Rails • ActionController

Filtering parameters (Basic)

class UsersController < ApplicationController def index respond_to do |format| format.html do render html: "Hello #{ user_params[:name] } user_params[:sentence]" end end end private def user_params if params[:name] == "john&quo...

Ruby on Rails • ActionController

Using GET with parameters

This function runs an AJAX call using GET allowing us to send parameters (object) to a file (string) and launch a callback (function) when the request has been ended. function ajax(file, params, callback) { var url = file + '?'; // loop through object and assemble the url var notFirst ...

JavaScript • AJAX

Viewing a three-way merge including the common ancestor

git config --global merge.conflictstyle diff3 Sets the diff3 style as default: instead of the usual format in conflicted sections, showing the two files: <<<<<<< HEAD left ======= right >>>>>>> master it will include an additional section containi...

Git • Git Diff

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

Multiple type parameters

Generics types can have more than one type parameters, eg. Result is defined like this: pub enum Result<T, E> { Ok(T), Err(E), }

Rust • Generics

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

Member initialization

Each of the enum members may be initialized with a value. If a value is not specified for a member, by default it's initialized to 0 (if it's the first member in the member list) or to a value greater by 1 than the value of the preceding member. Module Module1 Enum Size Small ...

Visual Basic .NET Language • Enum

No return statement for a function with a non-void return type

Omitting the return statement in a function which is has a return type that is not void is undefined behavior. int function() { // Missing return statement } int main() { function(); //Undefined Behavior } Most modern day compilers emit a warning at compile time for this kind o...

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)

Rename Folders

To rename a folder from oldName to newName git mv directoryToFolder/oldName directoryToFolder/newName Followed by git commit and/or git push If this error occurs: fatal: renaming 'directoryToFolder/oldName' failed: Invalid argument Use the following command: git mv directoryToFolder/oldN...

Git • Renaming

Remove non alphanumeric characters from string

public string Remove() { string input = "Hello./!"; return Regex.Replace(input, "[^a-zA-Z0-9]", ""); }

.NET Framework • Regular Expressions (System.Text.RegularExpressions)

Extension methods as strongly typed wrappers

Extension methods can be used for writing strongly typed wrappers for dictionary-like objects. For example a cache, HttpContext.Items at cetera... public static class CacheExtensions { public static void SetUserInfo(this Cache cache, UserInfo data) => cache["UserInfo"] ...

C# Language • Extension Methods

OutOfMemoryError

This is a runtime error that happens when you request a large amount of memory on the heap. This is common when loading a Bitmap into an ImageView. You have some options: Use a large application heap Add the "largeHeap" option to the application tag in your AndroidManifest.xml. This...

Android • Exceptions

Accessing members of struct

In Swift, structures use a simple “dot syntax” to access their members. For example: struct DeliveryRange { var range: Double let center: Location } let storeLocation = Location(latitude: 44.9871, longitude: -93.2758) var pizzaRange = DeliveryRange(range: 200...

Swift Language • Structs

Databinding in Fragment

Data Model public class Item { private String name; public String getName() { return name; } public void setName(String name){ this.name = name; } } Layout XML <?xml version="1.0" encoding="utf-8"?> <layout xmlns:an...

Android • Data Binding Library

Optional and Default Parameters

Optional Parameters In TypeScript, every parameter is assumed to be required by the function. You can add a ? at the end of a parameter name to set it as optional. For example, the lastName parameter of this function is optional: function buildName(firstName: string, lastName?: string) { // ...

TypeScript • Functions

Use Custom Theme Globally

In themes.xml: <style name="AppTheme" parent="Theme.AppCompat">  </style> In AndroidManifest.xml: <application android:icon="@mipmap/ic_launcher" android:label="@string/app_name" andr...

Android • Theme, Style, Attribute

Use Custom Theme Per Activity

In themes.xml: <style name="MyActivityTheme" parent="Theme.AppCompat">  </style> In AndroidManifest.xml: <application android:icon="@mipmap/ic_launcher" android:label="@string/app_name" ...

Android • Theme, Style, Attribute