Tutorial by Examples: i

fn foo<'a>(x: &'a u32) { // ... } This specifies that foo has lifetime 'a, and the parameter x must have a lifetime of at least 'a. Function lifetimes are usually omitted through lifetime elision: fn foo(x: &u32) { // ... } In the case that a function takes multiple ...

struct Struct<'a> { x: &'a u32, } This specifies that any given instance of Struct has lifetime 'a, and the &u32 stored in x must have a lifetime of at least 'a.

impl<'a> Type<'a> { fn my_function(&self) -> &'a u32 { self.x } } This specifies that Type has lifetime 'a, and that the reference returned by my_function() may no longer be valid after 'a ends because the Type no longer exists to hold self.x.

.Net 4.0 type Lazy guarantees thread-safe object initialization, so this type could be used to make Singletons. public class LazySingleton { private static readonly Lazy<LazySingleton> _instance = new Lazy<LazySingleton>(() => new LazySingleton()); public stati...

Using iris dataset: import sklearn.datasets iris_dataset = sklearn.datasets.load_iris() X, y = iris_dataset['data'], iris_dataset['target'] Data is split into train and test sets. To do this we use the train_test_split utility function to split both X and y (data and target vectors) randomly w...

Finding patterns in data often proceeds in a chain of data-processing steps, e.g., feature selection, normalization, and classification. In sklearn, a pipeline of stages is used for this. For example, the following code shows a pipeline consisting of two stages. The first scales the features, and t...

Different operations with data are done using special classes. Most of the classes belong to one of the following groups: classification algorithms (derived from sklearn.base.ClassifierMixin) to solve classification problems regression algorithms (derived from sklearn.base.RegressorMixin) to so...

A Service is a component which runs in the background (on the UI thread) without direct interaction with the user. An unbound Service is just started, and is not bound to the lifecycle of any Activity. To start a Service you can do as shown in the example below: // This Intent will be used to star...

await operator and async keyword come together: The asynchronous method in which await is used must be modified by the async keyword. The opposite is not always true: you can mark a method as async without using await in its body. What await actually does is to suspend execution of the code ...

1) BASIC SIMPLE WAY Database-driven applications often need data pre-seeded into the system for testing and demo purposes. To make such data, first create the seeder class ProductTableSeeder use Faker\Factory as Faker; use App\Product; class ProductTableSeeder extends DatabaseSeeder { pub...

You can download Mercurial from the project's website, and there are graphical utilities for Windows, Linux and OSX if you'd prefer that to a command line interface. Most Unix package managers include Mercurial, for example on Debian/Ubuntu: $ apt-get install mercurial You can verify Mercurial i...

Install-Package NUnit This package includes all assemblies needed to create unit tests. Tests can be executed using one of the following methods: Visual Studio Unit Test Window Console runner Third party runner that supports NUnit 3 Visual Studio Unit Test Window To execute tests using ...

The zero value of slice is nil, which has the length and capacity 0. A nil slice has no underlying array. But there are also non-nil slices of length and capacity 0, like []int{} or make([]int, 5)[5:]. Any type that have nil values can be converted to nil slice: s = []int(nil) To test whether a...

A callback is a method that gets called at specific moments of an object's lifecycle (right before or after creation, deletion, update, validation, saving or loading from the database). For instance, say you have a listing that expires within 30 days of creation. One way to do that is like this: ...

The Python Standard Library includes an interactive debugging library called pdb. pdb has extensive capabilities, the most commonly used being the ability to 'step-through' a program. To immediately enter into step-through debugging use: python -m pdb <my_file.py> This will start the debu...

PHP 7 introduces a new kind of operator, which can be used to compare expressions. This operator will return -1, 0 or 1 if the first expression is less than, equal to, or greater than the second expression. // Integers print (1 <=> 1); // 0 print (1 <=> 2); // -1 print (2 <=> 1...

The simple answer is that you cannot do this. Once an array has been created, its size cannot be changed. Instead, an array can only be "resized" by creating a new array with the appropriate size and copying the elements from the existing array to the new one. String[] listOfCities = ne...

setTimeout Executes a function, after waiting a specified number of milliseconds. used to delay the execution of a function. Syntax : setTimeout(function, milliseconds) or window.setTimeout(function, milliseconds) Example : This example outputs "hello" to the console after 1 secon...

This example illustrates how to create a simple program that will sum two int arrays with CUDA. A CUDA program is heterogenous and consist of parts runs both on CPU and GPU. The main parts of a program that utilize CUDA are similar to CPU programs and consist of Memory allocation for data that ...

import pandas as pd df = pd.DataFrame({'Sex': ['M', 'M', 'F', 'M', 'F', 'F', 'M', 'M', 'F', 'F'], 'Age': [20, 19, 17, 35, 22, 22, 12, 15, 17, 22], 'Heart Disease': ['Y', 'N', 'Y', 'N', 'N', 'Y', 'N', 'Y', 'N', 'Y']}) df Age Heart Disease Sex 0 20 ...