[Dan Man]

Hi,

I am trying to sort a multi-dimensional array.

The array is set up in such a way that the indexes are not consistent. For example:

PHP Code:

$the_array[2]["value"] = 3;

$the_array[1]["value"] = 7;

$the_array[4]["value"] = 1;

$the_array[10]["value"] = 10; 

I am trying to sort this array based on the value. I created a custom comparison function to use with usort(). It is below:

PHP Code:

function cmp($a, $b)

{

    if($a['value'] == $b['value'])

        return 0;



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

} 

Then in the code, I call:

PHP Code:

usort($the_array, "cmp"); 

The usort function, when comparing, seems to want to loop through all possible indexes.

That is, it will compare $the_array[0]["value"] even though it does not exist there is no index 0.

This is the observation I have made.

Any ideas of how to modify the function, or use something besides usort to accomplish the sorting on only the available indexes?

Thanks in advance!

[Nico]

How about:

PHP Code:

asort($the_array); 

Code:

Array
(
    [4] => Array
        (
            [value] => 1
        )

    [2] => Array
        (
            [value] => 3
        )

    [1] => Array
        (
            [value] => 7
        )

    [10] => Array
        (
            [value] => 10
        )

)

[Jay6390]

Originally Posted by Dan Man

That is, it will compare $the_array[0]["value"] even though it does not exist there is no index 0.

This is the observation I have made.

The problem is not that it tries the array index 0, its that it returns the array sorted and doesnt keep the original keys. it returns the following

Code:

Array
(
    [0] => Array
        (
            [value] => 1
        )

    [1] => Array
        (
            [value] => 3
        )

    [2] => Array
        (
            [value] => 7
        )

    [3] => Array
        (
            [value] => 10
        )

)

As you can see, it just assigns new index values starting at 0

Use the code Nico provided instead
Jay

[Nico]

Yep, Jay got that right. And on a further note, you could also use your existing function, along with uasort(), to maintain the indexes. But I'd rather use asort() alone, unless you have some specific reason why you prefer doing it the other way.

[Dan Man]

Thanks Nico and Jay!

The uasort was exactly what I was looking for!

I forgot to mention that my array hold multiple keys, so I wasn't sure how asort would treat that.

That is:

PHP Code:

$the_array[2]["value"] = 3;
$the_array[2]["rank"] = 1;
$the_array[1]["value"] = 7;
$the_array[1]["rank"] = 3; 

etc. I am still curious how asort would treat this. Could you specify a key for it to sort by?

Thanks again!

[Jay6390]

you mean something like

PHP Code:

<?php
$the_array[2]["value"] = 3;
$the_array[2]["rank"] = 1;
$the_array[1]["value"] = 7;
$the_array[1]["rank"] = 3;

foreach($the_array as $k=>$v)
{
asort($the_array[$k]);
}
ksort($the_array);
echo "<pre>".print_r($the_array,true)."</pre>";
?>

gives the output

Code:

Array
(
    [1] => Array
        (
            [rank] => 3
            [value] => 7
        )

    [2] => Array
        (
            [rank] => 1
            [value] => 3
        )

)

If you want to sort the subkeys in the arrays by the actual keys rather than the values, replace asort with ksort for that also

Jay