flatMap()

The flatMap() method create a new array formed by applying function and then flattening the result by one level

Example.php

<?php use kim\present\utils\arrays\ArrayUtils;

$arrayUtils = ArrayUtils::from([-3, 2, -4, 5, 9]);

//Element duplication
$arrayUtils->flatMap(function($num){ return [$num, $num]; });
// expected output: [-3, -3, 2, 2, -4, -4, 5, 5, 9, 9]

//Remove negative and split the odd numbers into an even number and a 1
$arrayUtils->flatMap(function($num){
  if($num< 0)       return [];
  if($num % 2 == 0) return [$num];
  else              return [$num - 1, 1]; });
// expected output: [2, 4, 1, 8, 1]

Syntax

$arrayUtils->flatMap(callable $callback) : ArrayUtils;

Parameter

• $callback

  A function that produces an element of the new Array, taking three arguments:

  • $value The current element being processed in the array.

  • $key The index of the current element being processed in the array.

  • $array The array every was called upon.

Return value

• A new array with each element being the result of the callback function and flattened to a depth of 1.

Prefixing

$arrayUtils->flatMapAs(callable $callback) : array;

ArrayUtils::flatMapFrom(iterable $from, callable $callback) : ArrayUtils;

ArrayUtils::flatMapFromAs(iterable $from, callable $callback) : array;

References

Array.prototype.flatMap() - JavaScript | MDN