sort multidimensional array twice

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

那会行得通，但是如果您使用稳定的排序算法，则可以先按距离排序，然后按赞助商降序排序，您将获得所需的结果。

Answer 4

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 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);
  ?>