Ranking/Position on value of array in PHP

Question

I have an array with these values, Array ( [0] => 12 [1] => 17 [2] => 5 [3] => 27 [4] => 5 ) and I need to find out ranking/position of each value ie,

for 27 - Rank 1 
for 17 - Rank 2 
for 12 - Rank 3 
for 5 - Rank 4 
for 5 - Rank 4 (duplicate value in the array)

and these need to be in the same order as the array, so that output should be as follow

12 - Rank 3 
17 - Rank 2 
5 - Rank 4 
27 - Rank 1 
5 - Rank 4

How is 27 Rank 2? I don't get it? You only know that 27 has the array key 3 and is therefore at the fourth position in your array. — Andresch Serj, Apr 03 '14 at 08:07
Nobody will do your homework. Not because it's hard, but because you didn't try. You would need to fill another array in order to fill the values with their ranks. Using the same keys to not change the order. — Royal Bg, Apr 03 '14 at 08:11
"gapped rank" or "dense rank"? Your sample data isn't complex enough to offer this detail. — mickmackusa, Jul 25 '21 at 12:31
Related: [Get dense rank and gapped rank for all items in array](https://stackoverflow.com/a/72794015/2943403) — mickmackusa, Oct 23 '22 at 07:52

score 5 · Accepted Answer · answered Apr 03 '14 at 08:18

This should work (including duplicate values having the same rank):

$values = array();
$values[0] = 5;
$values[1] = 12;
$values[2] = 19;
$values[3] = 9;
$values[4] = 5;

$ordered_values = $values;
rsort($ordered_values);

foreach ($values as $key => $value) {
    foreach ($ordered_values as $ordered_key => $ordered_value) {
        if ($value === $ordered_value) {
            $key = $ordered_key;
            break;
        }
    }
    echo $value . '- Rank: ' . ((int) $key + 1) . '<br/>';
}

This answer is missing its educational explanation. – mickmackusa Jul 25 '21 at 12:24 — mickmackusa, Jul 25 '21 at 12:24

score 2 · Answer 2 · answered Apr 03 '14 at 08:45

2

try this

$array = Array ( "0" => 12 , "1" => 17 , "2" => 5, "3" => 27, "4" => 5 );

$i=1;
foreach($array as $key=>$values)
{
    $max = max($array);
    echo "\n".$max." rank is ". $i."\n";
    $keys = array_search($max, $array);    
    unset($array[$keys]);
    if(sizeof($array) >0)
    if(!in_array($max,$array))
        $i++;

}

Demo

answered Apr 03 '14 at 08:45

krishna

4,069
2
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56

This answer is missing its educational explanation. – mickmackusa Jul 25 '21 at 12:25

score 2 · Answer 3 · edited Sep 27 '22 at 12:20

Just came across this topic while looking for a nice solution for myself. Just drop this here for the future. What I'm using is the following function:

/* Assign rank to each value of the array $in. 
 * Args:
 *   in (array): Array containing as set of numeric values.
 *
 * Returns:
 *   Returns an array of the same length with ranks. Highest
 *   values of $in get rank 1, lower values get higher ranks.
 *   The same values are attributed to the same ranks.
 */
function array_rank( $in ) {
    # Keep input array "x" and replace values with rank.
    # This preserves the order. Working on a copy called $x
    # to set the ranks.
    print "input\n";
    print_r($in);
    $x = $in; arsort($x); 
    print "sorted\n";
    print_r($x);
    # Initival values
     $rank       = 0; 
    $hiddenrank = 0;
    $hold = null;
    foreach ( $x as $key=>$val ) {
        # Always increade hidden rank
        $hiddenrank += 1;
        # If current value is lower than previous:
        # set new hold, and set rank to hiddenrank.
        if ( is_null($hold) || $val < $hold ) {
            $rank = $hiddenrank; $hold = $val;
        }    
        # Set rank $rank for $in[$key]
        $in[$key] = $rank;
    }  
    print "ranking result\n";
    print_r($in);
    return $in; 
}
$a = array(140,180,180,100);
array_rank( $a );

The print statements (development) return the following:

input
Array
(
   [0] => 140
    [1] => 180
    [2] => 180
    [3] => 100
)
sorted
Array
(
    [2] => 180
    [1] => 180
    [0] => 140
    [3] => 100
)
ranking result
Array
(
    [0] => 3
    [1] => 1
    [2] => 1
    [3] => 4
)

In case you want to have a reverse ranking (lower values are better) simply replace arsort with asort. In my case I am ranking points, the higher the better. The array (140,180,180,100) gets the ranks (3,1,1,4). Players with the same amount of points get the same rank (in this case rank 1) while rank 2 is left out.

score 0 · Answer 4 · answered Apr 03 '14 at 08:11

You can probably sort the array by the values:

$ranked = sort($arrayValues);

after this, you can do a for loop, looping through the $ranked array, then printing the arrays in order:

for($i = 0; $i < length($ranked); $i++){
    for($j = 0; $j < length($arrayValues); $j++){
        if($arrayValues[$i] == $sorted[$j]){
            echo $arrayValues[$i] . ' has rank ' . $j;
         }
    }
}

score 0 · Answer 5 · answered Apr 03 '14 at 08:16

one problem you have is that you want some return value that has 2 times an identical value and key (5=>rank4). So you cannot do an array with ranks as key nor with values as key. In this example i simply made a 2 dimensional array.

<?php

error_reporting(E_ALL | E_STRICT);
ini_set('display_errors', 1);

// your original input
$original = array(12, 17, 5, 27, 5);

// strip duplicates as they are ranked equally
$rankings = array_unique($original);

// apply some sorting so that the ranks are now given by the keys.
rsort($rankings);

// now just use the origincal array and lookup the rankings for each value
$return = array();
foreach($original as $value)
{
    $rankedValue = array();
    $rankedValue['value'] = $value;
    $rankedValue['rank'] = array_search($value, $rankings) + 1;
    $return[] = $rankedValue;
}

var_dump($return);

Ranking/Position on value of array in PHP

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