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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

​
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flat()
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flip()
Last modified 2yr ago