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The %timeit magic runs the given code many times, then returns the speed of the fastest result. In [1]: %timeit sum(range(100000)) 100 loops, best of 3: 2.91 ms per loop The %%timeit cell magic can be used to time blocks of code. In [2]: %%timeit ...: a = 0 ...: for i in range(100000):...

R provides two additional looping constructs, while and repeat, which are typically used in situations where the number of iterations required is indeterminate. The while loop The general form of a while loop is as follows, while (condition) { ## do something ## in loop body } whe...

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The Collections class allows for you to move objects around in the list using various methods (ls is the List): Reversing a list: Collections.reverse(ls); Rotating positions of elements in a list The rotate method requires an integer argument. This is how many spots to move it along the line b...

Suppose we have a component which will hide at a certain window width. import { Component } from '@angular/core'; @Component({ ... template: ` <div> <p [hidden]="!visible" (window:resize)="onResize($event)" >Now you see me...</p> &lt...

Using parameters passed by reference An event may define a ByRef parameter meant to be returned to the caller: Public Event BeforeSomething(ByRef cancel As Boolean) Public Event AfterSomething() Public Sub DoSomething() Dim cancel As Boolean RaiseEvent BeforeSomething(cancel) If...

For expressing the power of 2 (2^n) of integers, one may use a bitshift operation that allows to explicitly specify the n. The syntax is basically: int pow2 = 1<<n; Examples: int twoExp4 = 1<<4; //2^4 int twoExp5 = 1<<5; //2^5 int twoExp6 = 1<<6; //2^6 ... int twoEx...

The "right-left" rule is a completely regular rule for deciphering C declarations. It can also be useful in creating them. Read the symbols as you encounter them in the declaration... * as "pointer to" - always on the left side [] as "array of" ...

To get a value associated to the key, use the .get() method. If there's no value associated to the key, it returns undefined. const obj1 = {}, obj2 = {}; const weakmap = new WeakMap([[obj1, 7]]); console.log(weakmap.get(obj1)); // 7 console.log(weakmap.get(obj2)); // undefined

To assign a value to the key, use the .set() method. It returns the WeakMap object, so you can chain .set() calls. const obj1 = {}, obj2 = {}; const weakmap = new WeakMap(); weakmap.set(obj1, 1).set(obj2, 2); console.log(weakmap.get(obj1)); // 1 console.log(weakmap.get(obj2)); // 2 ...

To check if an element with a specified key exits in a WeakMap, use the .has() method. It returns true if it exits, and otherwise false. const obj1 = {}, obj2 = {}; const weakmap = new WeakMap([[obj1, 7]]); console.log(weakmap.has(obj1)); // true console.log(weakmap.has(obj2)); // false...

To remove an element with a specified key, use the .delete() method. It returns true if the element existed and has been removed, otherwise false. const obj1 = {}, obj2 = {}; const weakmap = new WeakMap([[obj1, 7]]); console.log(weakmap.delete(obj1)); // true console.log(weakmap.has(obj...

Recommendation Because the symbols i and j can represent significantly different things in MATLAB, their use as loop indices has split the MATLAB user community since ages. While some historic performance reasons could help the balance lean to one side, this is no longer the case and now the choice...

You can override the default vmoptions with your own personal settings by choosing Help > Edit Custom VM Options from the toolbar. This will create a local copy of the file which you are free to edit. For example, if you double the value set for Xmx, the maximum size of the memory allocation poo...

This example shows the base of almost any XSLT transformation and the most fundamental XSLT design pattern. Producing as output an XML document that is identical to the source XML document. Source XML document: <t>Hello, World!</t> XSLT transformation: <xsl:stylesheet version=&q...

In the following code let us assume for simplicity that float and uint32_t have the same size. void fun(uint32_t* u, float* f) { float a = *f *u = 22; float b = *f; print("%g should equal %g\n", a, b); } u and f have different base type, and thus the compiler can a...

The loop macro supports iteration over the keys, the values, or the keys and values of a hash table. The following examples show possibilities, but the full loop syntax allows more combinations and variants. Over keys and values (let ((ht (make-hash-table))) (setf (gethash 'a ht) 1 (g...

The keys and values of a hash table can be iterated over using the macro with-hash-table-iterator. This may be a bit more complex than maphash or loop, but it could be used to implement the iteration constructs used in those methods. with-hash-table-iterator takes a name and a hash table and binds...

The FileSystem API of Java 7 allows to read and add entries from or to a Zip file using the Java NIO file API in the same way as operating on any other filesystem. The FileSystem is a resource that should be properly closed after use, therefore the try-with-resources block should be used. Reading ...

A problem: Canvas only remembers pixels, not shapes or images This is an image of a circular beach ball, and of course, you can't drag the ball around the image. It may surprise you that just like an image, if you draw a circle on a Canvas you cannot drag that circle around the canvas. That's be...