How do I sort a PHP array by an element nested inside?

Question

I have an array like the following:

Array
(
    [0] => Array
        (
            \'name\' => \"Friday\"
            \'weight\' => 6
        )
    [1] => Array
          


        

Answer 1

Here's a cool function that might help:

function subval_sort($a,$subkey,$sort) {
    foreach($a as $k=>$v) {
        $b[$k] = strtolower($v[$subkey]);
    }
    if($b)
    {
        $sort($b);
        foreach($b as $key=>$val) {
            $c[] = $a[$key];
        }
        return $c;
    }
}

Send in the array as $a the key as $subkey and 'asort' or 'sort' for the $sort variable

Answer 2

try this: http://php.net/manual/en/function.usort.php

Answer 3

Can be done using an anonymous function.

Also if your 'weight' is a string use one of the other returns (see the commented out lines):

<?php

$arr = array(
    0 => array (
        'name'   => 'Friday',
        'weight' => 6,
    ),
    1 => array (
        'name'   => 'Monday',
        'weight' => 2,
    ),
);

// sort by 'weight'
usort($arr, function($a, $b) { // anonymous function
    // compare numbers only
    return $a['weight'] - $b['weight'];

    // compare numbers or strings
    //return strcmp($a['weight'], $b['weight']);

    // compare numbers or strings non-case-sensitive
    //return strcmp(strtoupper($a['weight']), strtoupper($b['weight']));
});

var_export($arr);

/*
array (
    0 => array (
        'name'   => 'Monday',
        'weight' => 2,
    ),
    1 => array (
        'name'   => 'Friday',
        'weight' => 6,
    ),
)
*/

Answer 4

If the filed you sort by is string like title name,
array_multisort + Flags for Natural Sorting and CaseInSensitivity are the way to go:

$sort_by_title = array();
foreach($items as $item) {
  $sort_by_title [] = $item['title'];
}
array_multisort($sort_by_title , SORT_ASC, SORT_NATURAL | SORT_FLAG_CASE, $items );

Answer 5

You can also use an anonymous function.

usort($items, function($a, $b) {
    return $a['name'] > $b['name'];
});

Answer 6

Agree with usort, I also sometimes use array_multisort (http://ca2.php.net/manual/en/function.usort.php) example 3, sorting database results. You could do something like:

<?php
$days = array(
  array('name' => 'Friday', 'weight' => 6),
  array('name' => 'Monday', 'weight' => 2),
);

$weight = array();
foreach($days as $k => $d) {
  $weight[$k] = $d['weight'];
}

print_r($days);

array_multisort($weight, SORT_ASC, $days);

print_r($days);
?>

Output:

Array
(
    [0] => Array
        (
            [name] => Friday
            [weight] => 6
        )

    [1] => Array
        (
            [name] => Monday
            [weight] => 2
        )

)
Array
(
    [0] => Array
        (
            [name] => Monday
            [weight] => 2
        )

    [1] => Array
        (
            [name] => Friday
            [weight] => 6
        )

)