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1

I need help sorting an associative array with PHP.

The sorting should rely on the array key "name", and keep the key/value pairs. Following sorting order: 1) first integer ASC, 2) second integer ASC, 3) third mixed ASC

input

array(6) {
  [0]=>
  array(2) {
    ["name"]=>
    string(13) "60 to 90 in 6"
    ["timing"]=>
    float(4.7)
  }
  [1]=>
  array(2) {
    ["name"]=>
    string(15) "40 to 120 in KD"
    ["timing"]=>
    float(3.3)
  }
  [2]=>
  array(2) {
    ["name"]=>
    string(14) "60 to 100 in 4"
    ["timing"]=>
    float(1.5)
  }
  [3]=>
  array(2) {
    ["name"]=>
    string(13) "60 to 90 in 4"
    ["timing"]=>
    float(2.4)
  }
  [4]=>
  array(2) {
    ["name"]=>
    string(15) "140 to 160 in 6"
    ["timing"]=>
    float(2.4)
  }
  [5]=>
  array(2) {
    ["name"]=>
    string(13) "60 to 90 in KD"
    ["timing"]=>
    float(5.7)
  }
}

output order

1, 3, 0, 5, 2, 4

Thank you very much for your help.

Answer:

uasort($acceleration, function($a, $b) {    
    if($a['_sort'][0] == $b['_sort'][0] AND $a['_sort'][2] == $b['_sort'][2])
    {                       
        if($a['_sort'][4] < $b['_sort'][4])
            return -1;
        elseif($a['_sort'][4] > $b['_sort'][4])
            return 1;
        else
            return 0;
    }
    elseif($a['_sort'][0] == $b['_sort'][0])
    {
        if($a['_sort'][2] < $b['_sort'][2])
            return -1;
        elseif($a['_sort'][2] > $b['_sort'][2])
            return 1;
        return 0;
    }
    else
    {
        if($a['_sort'][0] < $b['_sort'][0])
            return -1;
        elseif($a['_sort'][0] > $b['_sort'][0])
            return 1;
        else
            return 0;
    }
});

I'm sure, there is a more elegant way, but may serve as input.

share|improve this question
    
Where's your code? What have you done so far? We can try to help you with your code, but we can't write it for you. – Uby Mar 28 '13 at 20:45
up vote 0 down vote accepted

You need array_keys of this array after sorted with uasort(). The comparison function(closure) should be easy to write.

share|improve this answer
    
Since you will use string processing for the comparison, you may want to cache the "meaning" of the "name" values if you expect large amount of data: before sorting, insert the to each item the 3 values required for sorting, e.g. for the first, add '_sort'=>array(60,90,'6'), second '_sort'=>array(40,120,'KD')... – Levente Pánczél Mar 28 '13 at 20:57
    
Thx for the inputs. – aebersold Mar 28 '13 at 22:41
up vote 0 down vote

You should use usort() which allows you to use user-defined comarison function for sorting. So you have to implement function which compares the neme fields and return -1,0 or 1 value depending on the result (less then, equals or greater then). This function may use regex to get three values from name strng field and then compare them using your conditions.

share|improve this answer
    
Two bad advices in a row. First, usort() does not maintain the keys, which would be the result. Second, don't use regexp; especially not for strings that don't require it; if you're sure of the strings very fixed format, go with explode(). – Levente Pánczél Mar 28 '13 at 20:52
up vote 0 down vote 
<?php

$acceleration = array();
$acceleration[0]= array("name" => "60 to 90 in 6",   "timing" => 4.7 );
$acceleration[1]= array("name" => "40 to 120 in KD", "timing" => 3.3 );
$acceleration[2]= array("name" => "60 to 100 in 4",  "timing" => 1.5 );
$acceleration[3]= array("name" => "60 to 90 in 4",   "timing" => 2.4 );
$acceleration[4]= array("name" => "140 to 160 in 6", "timing" => 2.4 );
$acceleration[5]= array("name" => "60 to 90 in KD",  "timing" => 5.7 );


function comp_maker( $key ) {
    return function ($a, $b) use ( $key ) {     // closure for uasort() to use
        return strnatcmp( $a[$key], $b[$key] ); // comp by "natural order" 
    };
}

uasort($acceleration, comp_maker( 'name' ) );

// display sorted array's keys 
$str = '';
foreach ( $acceleration as $key => $value ){
    $str .= ", $key";
}
echo substr($str,1);

// output:  1, 3, 0, 5, 2, 4

You may also look at the code here

This solution follows the sage advice about applying uasort() which is more appropriate than usort() since it preserves the array's key-value associations. Without these being maintained, the results would be: 0,1,2,3,4,5 which conceal how the original array was reordered.

Note that the second parameter for uasort() will evaluate as a closure as a result of invoking the comp_maker() function. uasort() in turn will invoke the closure so that it may perform the comparison. The sorting occurs according to "human order" by means of using strnatcmp(), so the values appear in ascending order as one would expect.

To obtain the results, I could have used array_keys() but chose instead to avoid the overhead of a function call by iterating through the array using key,value syntax to output the new order of the sorted array's keys.

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