Sort multidimensional array in PHP using foreach

Question

For example i have an array named $slice like this :

Array
(
    [0] => Array
        (
            [0] => 12
            [1] => 4
            [2] => 2
            [3] => 8
            [4] => 20
        )

    [1] => Array
        (
            [0] => 9
            [1] => 7
            [2] => 1
            [3] => 10
            [4] => 23
        )

)

I want to sort array above so the output will be like this :

Array
    (
        [0] => Array
            (
                [0] => 2
                [1] => 4
                [2] => 8
                [3] => 12
                [4] => 20
            )

        [1] => Array
            (
                [0] => 1
                [1] => 7
                [2] => 9
                [3] => 10
                [4] => 23
            )

    )

Then i tried to use foreach and array_multisort, and when i use print_r the result is 1 for each col :

foreach ($slice1 as $col) {
    $slicesort[] = array_multisort($col);
}

output :
Array
(
    [0] => 1
    [1] => 1
)

From the documentation: array_multisort() can be used to sort several arrays at once, or a multi-dimensional array by one or more dimensions. You're not sorting a multi-dimensional array; you're sorting elements of a multidimensional array. — Patrick White
– Patrick White, Commented Aug 25, 2016 at 13:43

deceze · Accepted Answer · 2016-08-25 13:42:24Z

4

array_multisort sorts the array in place, it does not return the sorted array. You need to use it like this:

foreach ($slice1 as $col) {
    array_multisort($col);
    $slicesort[] = $col;
}

Having said this, array_multisort is somewhat overkill here, and I'm not sure that you really need to create a copy of the array. This will do just fine:

foreach ($slice1 as &$col) {
    sort($col);
}

This applies sort to each array within $slice1 by reference, and thereby orders $slice1 in place.

answered Aug 25, 2016 at 13:42

deceze♦

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1 Comment

Matt Raines Over a year ago

It's useful to unset($col); after the foreach loop in your second solution so you don't inadvertently overwrite the array if you use another variable called $col later in the script.

Riccardo · Accepted Answer · 2016-08-25 13:47:03Z

1

PHP array_multisort, as per the documentation, is for sorting multiple or multi-dimensional arrays, in your case you don't really need it. In your case you just need sort, you can find the documentation here

$slicesort = array();
foreach ($slice1 as $col) {
    sort($col);
    $slicesort[] = $col;
}

edited Aug 25, 2016 at 13:47

answered Aug 25, 2016 at 13:41

Riccardo

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Comments

Don't Panic · Accepted Answer · 2016-08-25 14:04:13Z

1

$slice = array(
    array(12,4,8,2,10),
    array(9,7,1,10,13)
    );

foreach ($slice as &$arr) {
    sort($arr);
}

print_r($slice);

edited Aug 25, 2016 at 14:04

Don't Panic

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answered Aug 25, 2016 at 13:54

Yogesh Singasane

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Comments

Mariella · Accepted Answer · 2016-08-25 13:50:03Z

0

array_multisort return a boolean value, true for success, false otherwise.

Change your code this way:

foreach ($slice1 as $col) {
    if (array_multisort($col)) {
        $slicesort[] = $col;
    }
}

answered Aug 25, 2016 at 13:50

Mariella

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