How to sort a multi-dimensional array by value

Let there is an array as follow:

Array
(
[0] => Array
(
[hashtag] => a7e87329b5eab8578f4f1098a152d6f4
[title] => Flower
[order] => 3
)

[1] => Array
(
[hashtag] => b24ce0cd392a5b0b8dedc66c25213594
[title] => Free
[order] => 2
)

[2] => Array
(
[hashtag] => e7d31fc0602fb2ede144d18cdffd816b
[title] => Ready
[order] => 1
)
)


If you are still on PHP 5.2 or earlier, you’ll have to define a sorting function first:

function sortByOrder($a, $b) {
return $a[‘order’] – $b[‘order’];
}

usort($myArray, ‘sortByOrder’);


Starting in PHP 5.3, you can use an anonymous function:

usort($myArray, function($a, $b) {
return $a[‘order’] – $b[‘order’];
});


And finally with PHP 7 you can use the “spaceship operator”:

usort($myArray, function($a, $b) {
return $a[‘order’] <=> $b[‘order’];
});


To extend this to multi-dimensional sorting, reference the second/third sorting elements if the first is zero – best explained below. You can also use this for sorting on sub-elements.

usort($myArray, function($a, $b) {
$retval = $a[‘order’] <=> $b[‘order’];
if ($retval == 0) {
$retval = $a[‘suborder’] <=> $b[‘suborder’];
if ($retval == 0) {
$retval = $a[‘details’][‘subsuborder’] <=> $b[‘details’][‘subsuborder’];
}
}
return $retval;
});


*If you need to retain key associations, use uasort() – see comparison of array sorting functions in the manual.

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Posted in PHP

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