PHP sort highest number to lowest for chart

Question

I'm creating a CSS chart that lists items from highest to lowest based on the number value. The problem is "rsort" seems to only count the first 5 digits (or so it seems). This is resulting in it showing items higher than 100,000 below the other numbers. Example of this problem is below:

$ITEM_1 = "95000";
$ITEM_2 = "103000";
.. 

$item_rank[]= "<li>$ITEM_1 Item 1</li>";
$item_rank[]= "<li>$ITEM_2 Item 2</li>";
..

rsort($item_rank); // sort highest numbers to lowest

echo "<ul>";     
echo $item_rank[0];
echo $item_rank[1];
 ..
echo "</ul>";

In this case, Item 1 is actually a lower number, but it is being ranked higher because any item over 100,000 gets treated lower. Is there a way around this?

Answer 1

I believe you should be using natsort() . This happens when you try to sort numbers treated as string. Here's an example:

$a=array('1a','2a','3a','10a','15a');
rsort($a);
echo implode(',',$a); // outputs 3a,2a,1a,15a,10a

But you are expecting an output like this:

15a,10a,3a,2a,1a

To do that, use natsort and array_reverse() :

$a=array('1a','2a','3a','10a','15a');

natsort($a);
$a=array_reverse($a);

echo implode(',',$a); // outputs 15a,10a,3a,2a,1a

Answer 2

Since the $item_rank array has string values, rsort will sort it in alphabetic order. In alphabetic order reverse sort, "2" will come before "10" even though 10 > 2.

You need to implement natsort for this type of sorting. Check - http://us3.php.net/manual/en/function.natsort.php

The example from php.net:

<?php
    $array1 = $array2 = array("img12.png", "img10.png", "img2.png", "img1.png");

    asort($array1);
    echo "Standard sorting\n";
    print_r($array1);

    natsort($array2);
    echo "\nNatural order sorting\n";
    print_r($array2);
?>

Standard sorting
Array
(
[3] => img1.png
[1] => img10.png
[0] => img12.png
[2] => img2.png
)

Natural order sorting
Array
(
[3] => img1.png
[2] => img2.png
[1] => img10.png
[0] => img12.png
)