How to sort associative array? - php

Question

I have associative array. On print_f($array_name), I got this
Array (
[0] => Array (
[teamid] => abc
[distance] => 1.25
)
[1] => Array (
[teamid] => xyz
[distance] => 0.25
)
)
This is that array which I want to sort according to distance. eg, This should be look like this after sorting,
Array (
[0] => Array (
[teamid] => xyz
[distance] => 0.25
)
[1] => Array (
[teamid] => abc
[distance] => 1.25
)
)
If anyone know answer then please explain or suggest me link from where I can understand from beginning. Thank You.

Answer 1

Here is what you need to do.
$a = array(array( 'teamid' => 'abc', 'distance' => 1.25 ), array( 'teamid' => 'xyz', 'distance' => 0.25 ));
$distance = array();
foreach ($a as $key => $row)
{
$distance[$key] = $row['distance'];
}
array_multisort($distance, SORT_ASC, $a);
print_r($a);
This outputs
Array
(
[0] => Array
(
[teamid] => xyz
[distance] => 0.25
)
[1] => Array
(
[teamid] => abc
[distance] => 1.25
)
)
source Example #3 Sorting database results
DEMO
Edit
as per Mike's comment,
here are two answers,
one tells that on single array you should use usort(as Mike's answer) and array_multisort is used to compare elements from different arrays (or sub-arrays) at the same time.
in the other answer, as Mike wants some bench marking
usort() is more concise and doesn't require extracting a column array to feed to array_multisort(). (It also does less than array_multisort.)
However, when I repeatedly tested it today on arrays of 20,000 and
10,000 representative data rows, usort() was 7-15x slower than
array_multisort() when the column was random values of type int and
the column was pre-extracted. That is as one might expect, since for
every comparison you're comparing an entire php function call to
optimized intrinsic code.
more about bench marking notes, read full answer

Answer 2

$array = array(
array('teamid' => 'a', 'distance' => 1.25),
array('teamid' => 'b', 'distance' => 0.25),
array('teamid' => 'c', 'distance' => 2.5),
array('teamid' => 'd', 'distance' => 0.75),
);
function cmp($a, $b)
{
if ($a['distance'] == $b['distance']) return 0;
return ($a['distance'] < $b['distance']) ? -1 : 1;
}
usort($array, "cmp");
More info: http://php.net/usort