Tutorial by Examples: r

The policy builder allows you to build sophisticated policies. app.UseCors(builder => { builder.WithOrigins("http://localhost:5000", "http://myproductionapp.com") .WithMethods("GET", "POST", "HEAD") .WithHeaders(&quo...

Let's say you have a table called person: CREATE TABLE person ( person_id BIGINT NOT NULL, last_name VARCHAR(255) NOT NULL, first_name VARCHAR(255), age INT NOT NULL, PRIMARY KEY (person_id) ); You can create a new table of people over 30 like this: CREATE TABLE p...

Intellij IDEA attempts to appeal to the wide Java fanbase which uses Eclipse for their development by allowing developers to migrate their Eclipse projects over to an IDEA structure with a few simple clicks! First, start IDEA and click Import Project from the startup window: Then, select your Ec...

Date always have a different format, they can be parsed using a specific parse_dates function. This input.csv: 2016 06 10 20:30:00 foo 2016 07 11 19:45:30 bar 2013 10 12 4:30:00 foo Can be parsed like this : mydateparser = lambda x: pd.datetime.strptime(x, "%Y %m %d %H:%M:%S...

Create a YAML file in the config/ directory, for example: config/neo4j.yml The content of neo4j.yml can be something like the below (for simplicity, default is used for all environments): default: &default host: localhost port: 7474 username: neo4j password: root development: ...

Navigator is React Native's default navigator. A Navigator component manages a stack of route objects, and provides methods for managing that stack. <Navigator ref={(navigator) => { this.navigator = navigator }} initialRoute={{ id: 'route1', title: 'Route 1' }} renderScene={this.ren...

Redux is the most common state management library used with React-Native. The following example demonstrates how to use the fetch API and dispatch changes to your applications state reducer using redux-thunk. export const fetchRecipes = (action) => { return (dispatch, getState) => { f...

One of the major benefit of Fourier Transform is its ability to inverse back in to the Time Domain without losing information. Let us consider the same Signal we used in the previous example: A1=10; % Amplitude 1 A2=10; % Amplitude 2 w1=2*pi*0.2; % Angular f...

Let's say we have a simple table called person: CREATE TABLE person ( person_id BIGINT, name VARCHAR(255). age INT, city VARCHAR(255) ); The most basic insert involves inserting all values in the table: INSERT INTO person VALUES (1, 'john doe', 25, 'new york'); If you wa...

You can insert multiple rows in the database at the same time: INSERT INTO person (name, age) VALUES ('john doe', 25), ('jane doe', 20);

You can insert data in a table as the result of a select statement: INSERT INTO person SELECT * FROM tmp_person WHERE age < 30; Note that the projection of the select must match the columns required for the insert. In this case, the tmp_person table has the same columns as person.

Beware that numbers can accidentally be converted to strings or NaN (Not a Number). JavaScript is loosely typed. A variable can contain different data types, and a variable can change its data type: var x = "Hello"; // typeof x is a string x = 5; // changes typeof x to...

When custom options are merged, they use the default strategy, which simply overwrites the existing value. If you want a custom option to be merged using custom logic, you need to attach a function to Vue.config.optionMergeStrategies: Vue.config.optionMergeStrategies.myOption = function (toVal, fro...

When a mixin and the component itself contain overlapping options, they will be “merged” using appropriate strategies. For example, hook functions with the same name are merged into an array so that all of them will be called. In addition, mixin hooks will be called before the component’s own hooks:...

Let's say you have a service the same as the one defined in the "First service and host" example. To create a client, define the client configuration section in the system.serviceModel section of your client configuration file. <system.serviceModel> <services> <cli...

Add the following pom to the dependencies section of your gradle build file : project.dependencies { compile 'org.roboguice:roboguice:3.+' provided 'org.roboguice:roboblender:3.+' }

You can inject any type of resource, Strings, Animations, Drawables, etc. To inject your first resource into an activity, you'll need to: Inherit from RoboActivity Annotate your resources with @InjectResource Example @InjectResource(R.string.app_name) String name; @InjectResource(R.drawa...

It was common practice to use NSRunLoop to show modal UIAlertView to block code execution until user input is processed in iOS; until Apple released the iOS7, it broke few existing apps. Fortunately, there is a better way of implementing it with C#’s async/await. Here’s the new code taking advantag...

User input Imagine you want a user to enter a number via input. You want to ensure that the input is a number. You can use try/except for this: Python 3.x3.0 while True: try: nb = int(input('Enter a number: ')) break except ValueError: print('This is not a num...

To change the appearance of the keyboard, the following types can be set individually on every UITextFields property: keyboardType typedef NS_ENUM(NSInteger, UIKeyboardType) { UIKeyboardTypeDefault, // Default type for the current input method. UIKeyboardTypeASCIICapable, ...