Using a Static Class Method to Quickly Sort an Array By Key Value in PHP

Question

This question is different than others, as it's focus is on sorting an array with a static class method rather than the typical procedural approach.

I am look for a very performant way to implement the function sortByKeyValue below. Other somewhat related answers are focused on getting the job done, this question is more about getting the job done and getting it done very quickly (as a static method).

Anyone want to take a crack at it? I'll probably throw some bounty on this question to squeeze out the performance junkies. :)

<?php

$data = array(
   array('name' => 'B', 'cheesy' => 'bacon'),
   array('name' => 'C', 'delicious' => 'tacos'),
   array('name' => 'A', 'lovely' => 'viddles'),
);

class MyArray {

    public static function sortByKeyValue($array, $key, $direction = 'ASC') {
        // Do the thing
        // Help me!

        return $array;
    }

}

$data = MyArray::sortByKeyValue($data, 'name');

// Should output the name key in order
// I am not including the garbage keys I threw in, but they should be there too)
// [{"name": "A"},{"name": "B"},{"name": "C"}]
?>

@insertusernamehere updated the question to reflect more than one key — Kirk Ouimet, Jul 17 '13 at 18:16

Orangepill · Answer 1 · 2013-07-17T18:22:04.587

3

You can use usort with a closure (Available php 5.3+)

 usort($array, function($a, $b){ return strcmp($a["name"], $b["name"]);});

Pre 5.3 you would have to create a sorter function and pass to usort

 function arraySorter($a, $b){
     return strcmp($a["name"], $b["name"]);
 }
 usort($array, "arraySorter");

Or you can place the arraySorter as a static method on your class

 public static function _arraySorter($a, $b){
     return strcmp($a["name"], $b["name"]); 
 }
 // then call
 usort($array, array("MyArray", "_arraySorter")); // for static

Note. This will perform an in place sort.

As Suggested by @Kirk in comments you can use a function to return an anonymous sorter function so the implementation isn't bound to the name property

function getSorter($property){
       return function($a, $b) use ($property){
           return strcmp($a[$property], $b[$property]);
       };
}

Then you can call

usort($array, getSorter("name"));

edited Jul 17 '13 at 18:22

answered Jul 17 '13 at 18:15

Orangepill

24,500
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How would you implement in pre 5.3 working with a static class? – Kirk Ouimet Jul 17 '13 at 18:18
1

@Kirk by wrapping it in a static method or passing the closure in as an array `array($this, $method)` – David Barker Jul 17 '13 at 18:19
What about making it dynamic so "name" isn't hard coded in the arraySorter method? – Kirk Ouimet Jul 17 '13 at 18:21
Regarding the updated array in the question, I think you have to check whether the `key` exists in the function, or it will throw an "*undefined index*" notice. For example if you sort by `cheesy`. – insertusernamehere Jul 17 '13 at 18:23
@Orangepill nice edits, PHP's looking more and more like JS as the years go by... :/ – David Barker Jul 17 '13 at 18:28

Expedito · Accepted Answer · 2013-07-17T21:44:40.227

I ran the following to compare the speed of multisort, a pre-PHP 5.3 method, with a more modern method that uses usort with a closure function:

$alpha = 'abcdefghijklmnopqrstuvwxyz';
$cnt = 1000;
$key = 'name';
$direction = 'ASC';
$array = array();
for ($i=0; $i<$cnt; $i++){
    $array[$i]['name'] = substr(str_shuffle($alpha), 0, 8);
    $array[$i]['job'] = substr(str_shuffle($alpha), 0, 8);
}
$pre = $array;//the test dummies

//PRE-PHP 5.3

$t[0] = -microtime();
$sub = array();
foreach ($pre as $item) {
        $sub[] = $item[$key];
}
if ($direction == 'ASC') $ord = SORT_ASC;
else $ord = SORD_DESC;
array_multisort($sub, $ord, $pre);
$t[0] += microtime();

//USORT WITH CLOSURE

$t[1] = -microtime();
usort($array, function ($a, $b) use($key, $direction){
    if ($direction == 'ASC'){
        return strcmp($a[$key], $b[$key]);
    }
    return strcmp($b[$key], $a[$key]);
});
$t[1] += microtime();
var_dump($t);

As you can see, the old method was more than twice as fast:

Array
(
    [0] => 0.005
    [1] => 0.014001
)

So here's how I would do the class:

class MyArray {

    public static function sortByKeyValue($array, $key, $direction = SORT_ASC) {
        $sub = array();
        foreach ($array as $item) {
            $sub[] = $item[$key];
        }
        array_multisort($sub, $direction, $array);
        return $array;
    }

}

score 1 · Answer 3 · answered Jul 17 '13 at 21:22

I prefer array_multisort():

<?php
$data = array(
   array('name' => 'B', 'cheesy' => 'bacon'),
   array('name' => 'C', 'delicious' => 'tacos'),
   array('name' => 'A', 'lovely' => 'viddles'),
);

class MyArray {

    public static function sortByKeyValue($array, $key, $direction = 'ASC') {

        $tmp = array();
        foreach($array as $k=>$r){
            $tmp[] = $r[$key];
        }
        array_multisort($tmp,($direction == 'ASC' ? SORT_ASC : SORT_DESC),$array);

        return $array;
    }

}

$data = MyArray::sortByKeyValue($data, 'name');

echo '<pre>',print_r($data),'</pre>';

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