Sort array by sub-array element value in PHP

Question

I'm using readdir to loop files into an array and getting back this result:

Array
(
  [0] => Array
    (
        [name] => /css
        [type] => directory
        [size] => 0
    )

  [1] => Array
    (
        [name] => /index.html
        [type] => file
        [size] => 1208
    )

  [2] => Array
    (
        [name] => /js
        [type] => directory
        [size] => 0
    )
)

My goal is to get them in typical 'file structure format' whereas it's ordered first by type (directories then files), then by name alphabetically.

How far have you gotten in this goal? Can you please show us what types of things you have tried? — Lix
– Lix, Commented Aug 30, 2012 at 20:29
Basically just wrapping it in sort() gets me the names alphabetically, I just can't figure out how to sort by directory/file — Fluidbyte
– Fluidbyte, Commented Aug 30, 2012 at 20:31
i would use glob() over readdir() - (especially as it has the coolest name for a php function.) — user557846
– user557846, Commented Aug 30, 2012 at 20:38

maaudet · Accepted Answer · 2012-08-30 21:01:50Z

1

function custom_order($a, $b)
{
    $type_cmp = -strcmp($b['type'], $a['type']);

    if ($type_cmp == 0)
    {
        return -strcmp($b['file'], $a['file']);
    }
    else
    {
        return $type_cmp;
    }
}

$test = array
(
  0 => array
    (
        'name' => '/css',
        'type' => 'directory',
        'size' => 0
    ),

  1 => array
    (
        'name' => '/index.html',
        'type' => 'file',
        'size' => 1208
    ),

  2 => array
    (
        'name' => '/js',
        'type' => 'directory',
        'size' => 0
    )
);

// http://www.php.net/manual/en/function.usort.php
usort($test, 'custom_order'); 

var_dump($test);

I have made a single-liner for fun. (Not that recommended in the name of code clarity)

function custom_order($a, $b)
{
    return ($type_cmp = -strcmp($b['type'], $a['type'])) === 0 ? -strcmp($b['file'], $a['file']) : $type_cmp;
}

edited Aug 30, 2012 at 21:01

answered Aug 30, 2012 at 20:42

maaudet

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1 Comment

Steve Robbins Over a year ago

I believe it should be return -$type_cmp;

ipoga · Accepted Answer · 2012-08-30 20:43:18Z

If you want to be sophisticated (which may not be necessary, given the circumstances - I assume you will have relatively few entries (~100) in each array), you should look into divide-and.conquer sorting algorithms for speed optimisation (see e.g. http://www.ics.uci.edu/~eppstein/161/960118.html or look in wikipedia for a general overview).

Sophistication aside, however, you can do like this:

function colSort(&$arr, $col, $dir = SORT_ASC) {
   $sort = array();
   foreach ($arr as $k => $r) {
     $sort[$k] = $r[$col];
   }
   array_multisort($sort, $dir, $arr);
 }

You can then use e.g. colSort($array, 'type'); to sort by type. The example can be further modified to sort by filesize or filename as well.

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