Get top 5 values from multidimensional array in PHP

Question

I have the following array:

Array ( 
[0] => Array ( 
    [count] => 9 
    [user_id] => 2 
) 
[1] => Array ( 
    [count] => 25 
    [user_id] => 1 
) 
[2] => Array ( 
    [count] => 20 
    [user_id] => 3 ) 
[3] => Array ( 
    [count] => 6 
    [user_id] => 56 ) 
[4] => Array ( 
    [count] => 2 
    [user_id] => 37 ) 
[5] => Array ( 
    [count] => 1 
    [user_id] => 0 
))

This is just a sample. The actual array will contain many more sub arrays.

I need to be able to obtain the top five values from "count" and store them with their associated "user_id".

The final result needs to look something like this:

Array ( 
[0] => Array ( 
    [count] => 25 
    [user_id] => 1 
) 
[1] => Array ( 
    [count] => 20 
    [user_id] => 3
) 
[2] => Array ( 
    [count] => 9 
    [user_id] => 2 
)   
[3] => Array ( 
    [count] => 6 
    [user_id] => 56 
)  
[4] => Array ( 
    [count] => 2 
    [user_id] => 37 
) 
[5] => Array ( 
    [count] => 1 
    [user_id] => 0 
) )

If this can be done by simply re ordering the array, that is fine.

Thanks!

The fact that it's multidimensional doesn't change the problem very much. You can still use quickselect, and use select sort for the last five elements. — , Jul 15 '11 at 16:01
@Gordon - The array is constructed from a database query and needs to be sorted after the query. — Pippin, Jul 15 '11 at 16:06
@user Add a `ORDER BY count DESC` clause to your SQL query. You can also add `LIMIT 5` to restrict it to the first five highest results. See http://dev.mysql.com/doc/refman/5.1/en/select.html — Gordon, Jul 15 '11 at 16:12

score 3 · Accepted Answer · answered Jul 15 '11 at 16:03

You're looking for usort and array_slice.

Example:

<?php

$array = array(
  array(
    'count' => 9,
    'user_id' => 2
  ),
  array(
    'count' => 25,
    'user_id' => 1
  ),
  array(
    'count' => 20,
    'user_id' => 3
  ),
  array(
    'count' => 6,
    'user_id' => 56
  ),
  array(
    'count' => 2,
    'user_id' => 37
  ),
  array(
    'count' => 1,
    'user_id' => 0
  )
);

function usort_callback($a, $b)
{
  if ( $a['count'] == $b['count'] )
    return 0;

  return ( $a['count'] > $b['count'] ) ? -1 : 1;
}

usort($array, 'usort_callback');

$top5 = array_slice($array, 0, 5);

print_r($top5);

Outputs:

Array
(
    [0] => Array
        (
            [count] => 25
            [user_id] => 1
        )

    [1] => Array
        (
            [count] => 20
            [user_id] => 3
        )

    [2] => Array
        (
            [count] => 9
            [user_id] => 2
        )

    [3] => Array
        (
            [count] => 6
            [user_id] => 56
        )

    [4] => Array
        (
            [count] => 2
            [user_id] => 37
        )

)

given that this is a blatant duplicate, you are encouraged to cv the question because it doesnt add any value to the community as a whole. — Gordon, Jul 15 '11 at 16:07

score 2 · Answer 2 · answered Jul 15 '11 at 16:02

2

usort($array, function ($a, $b) { return $b['count'] - $a['count']; });
$top5 = array_slice($array, 0, 5);

answered Jul 15 '11 at 16:02

deceze

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1

given that this is a blatant duplicate, you are encouraged to cv the question because it doesnt add any value to the community as a whole. – Gordon Jul 15 '11 at 16:06

Get top 5 values from multidimensional array in PHP

2 Answers2