how to rank array's index in PHP

问题

I need rank in my system. I have an array $arr = array(120,26,38,96,22);. I need to rank the index inside without changing their position.

The output I need is something like:

120 is rank 1, 26 is rank 4, 38 is rank 3, 96 is rank 2, 22 is rank 5

I've tried this, but all ranked as rank 1:

<?php
$arr = array(120,26,38,96,22);
$rank = 0;
$score=false;
$rows = 0;

foreach($arr as $sort){
    $rows++;
    if($score != $arr){
        $score = $arr;
        $rank = $rows;
    }echo $sort.' is rank '.$rank.'</br>';  
}
?>

And also I need the array length to be dynamic.

回答1:

Here's one way:

$arr  = array(120,26,38,96,22);
$rank = $arr;
rsort($rank);

foreach($arr as $sort) {
    echo $sort. ' is rank ' . (array_search($sort, $rank) + 1) . '</br>';
}

Copy the original array as $rank and sort in reverse so the keys will be the rank -1
Loop the original array and search for that value in $rank returning the key (rank)
Add 1 since keys start at 0

Or another possibility:

$arr  = array(120,26,38,96,22);
$rank = $arr;
rsort($rank);
$rank = array_flip($rank);

foreach($arr as $sort) {
    echo $sort . ' is rank '. ($rank[$sort] + 1) . '</br>';
}

Copy the original array as $rank and sort in reverse so the keys will be the rank -1
Flip the $rank array to get values as keys and rank as values
Loop the original array and use the value as the $rank key to get the rank
Add 1 since keys start at 0

回答2:

Do it like this:

$arr=array(120,26,38,96,22);
//get a copy adn use original for original order
$result=$arr;
//sort it numeric and reverse
rsort($result,SORT_NUMERIC);
//create the result
$result = array_map(function($a){return $a+1;},array_flip($result));
//print it
print_r($result);

Result:

Array ( [120] => 1 [96] => 2 [38] => 3 [26] => 4 [22] => 5 )

Get original order:

$resultxt = array();
foreach($arr as $sort){
  $resulttxt[] = $sort.' is rank '.$result[$sort];  
}
print implode(', ',$resulttxt).'<br>';

array_map http://php.net/manual/en/function.array-map.php

array_flip http://php.net/manual/en/function.array-flip.php

来源：https://stackoverflow.com/questions/41617333/how-to-rank-arrays-index-in-php

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php

ranking