sort multidimensional array twice - php

Question

I have sorted a multidimensional array on value distance from low to high. This is an example of the output: (the actual output has around 20 or 30 arrays).
Array
(
[0] => Array
(
[id] => 1
[distance] => 5
[sponsor] => 0
)
[1] => Array
(
[id] => 20
[distance] => 8
[sponsor] => 1
)
[2] => Array
(
[id] => 25
[distance] => 10
[sponsor] => 0
)
[3] => Array
(
[id] => 78
[distance] => 25
[sponsor] => 1
)
)
After sorting on distance from low to high, I want to give priority if sponsor = 1. This is the preferred output:
Array
(
[0] => Array
(
[id] => 20
[distance] => 8
[sponsor] => 1
)
[1] => Array
(
[id] => 78
[distance] => 25
[sponsor] => 1
)
[2] => Array
(
[id] => 1
[distance] => 5
[sponsor] => 0
)
[3] => Array
(
[id] => 25
[distance] => 10
[sponsor] => 0
)
)
Sponsor is either 0 or 1. How can I tackle this problem? I was thinking of, before sorting on distance, I should split up the array in 2 arrays based on sponsor (0,1), sort both arrays on distance, and then merge them with sponsor=1 at the top of the new multidimensional array. Is this the way to do it?
Thank you for your input.

Answer 1

This is slightly modified version of what usort suggests. Assuming source array is called $arr:
usort(
$arr, function($a, $b) {
if ( $a['sponsor'] == $b['sponsor'] ) {
if ( $a['distance'] == $b['distance'] ) {
return 0;
}
return $a['distance'] < $b['distance'] ? -1 : 1;
}
return $a['sponsor'] > $b['sponsor'] ? -1 : 1;
}
);

Answer 2

You have to split original array to 2 arrays: 1st has sponsor=1, 2nd has sponsor=0. Then sort them separately and merge.
Somehow like this:
$array1 = array_filter($array, function ($v) { return $v['sponsor'] == 1; });
$array2 = array_filter($array, function ($v) { return $v['sponsor'] == 0; });
function cmp($a, $b) {
return $a['distance'] < $b['distance']? -1 : 1;
}
usort($array1, cmp);
usort($array2, cmp);
$result = array_merge($array1, $array2);

Answer 3

You can use array_multisort() function to achieve what you want:
<?php
$arr = [
['id' => 1, 'distance' => 5, 'sponsor' => 0],
['id' => 20, 'distance' => 8, 'sponsor' => 1],
['id' => 25, 'distance' => 10, 'sponsor' => 0],
['id' => 78, 'distance' => 25, 'sponsor' => 1],
];
$sponsor = array_column($arr, 'sponsor');
$distance = array_column($arr, 'distance');
// rearrange $arr by sponsor DESC and then by distance ASC
array_multisort($sponsor, SORT_DESC, $distance, SORT_ASC, $arr);
print_r($arr);

Answer 4

That would work but if you use a stable sorting algorithm then you can sort first by distance, then by sponsor descending and you will get your desired results.

Answer 5

Try This :
<?php
$ar = array(
array("10", 11, 100, 100, "a"),
array( 1, 2, "2", 3, 1)
);
array_multisort($ar[0], SORT_ASC, SORT_STRING,
$ar[1], SORT_NUMERIC, SORT_DESC);
var_dump($ar);
?>
or
<?php
$ar1 = array(10, 100, 100, 0);
$ar2 = array(1, 3, 2, 4);
array_multisort($ar1, $ar2);
var_dump($ar1);
var_dump($ar2);
?>