Sort Multidimensional arrays by sub array key value

Question

There are similar questions and answers posted for this, but none of them quite match the structure of my array, so apologies if I missed something. This is an array generated by the WordPress wpdb class:

I need to list them by order of Array[meta_value]. Then I use the array to generate a table of products in that order. I have been working with the following function, but it produces a result that doesn't make any sense:

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

There is likely a way to do this in the query itself... just post how you are generating this information.. — jondavidjohn
– jondavidjohn, Commented Feb 21, 2013 at 3:32
Do you want to merge all these arrays before sort, or do you only want to sort them "inside their sub-array"? — Passerby
– Passerby, Commented Feb 21, 2013 at 3:47

Steely Wing · Accepted Answer · 2014-07-23 04:14:54Z

23

Use usort(), example:

$items = [
    ['id' => 3, 'item' => 'pc'],
    ['id' => 1, 'item' => 'mouse'],
    ['id' => 2, 'item' => 'kb'],
];

function compare_id($a, $b) {
    if ($a['id'] == $b['id']) return 0;
    return ($a['id'] < $b['id']) ? -1 : 1;
}

usort($items, 'compare_id');

var_dump($items);

or using anonymous function

usort($items, function ($a, $b) {
    if ($a['id'] == $b['id']) return 0;
    return ($a['id'] < $b['id']) ? -1 : 1;
});

edited Jul 23, 2014 at 4:14

answered Feb 21, 2013 at 3:45

Steely Wing

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1 Comment

Laci Over a year ago

This should be the accepted answer. Got it work in a blink of the eye!

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