ordering a php array by sorting one of its values

Question

I have an array of items that i want to sort by how many likes each item has with the highest first.

I tried to order the likes for each item, but in the way that i went about it, there was no more association to the original item.

Here is what i did:

$max = $feed->get_item_quantity(); //max number of items in the array
$orderedLike;
for($i = 0; $i < $max; $i++ )
{
    $item[$i] = $feed->get_item($i); //gets single items
    $orderedLike[$i] = $item[$i]->get_like_count(); //gets number of likes for each item
}
arsort($orderedLike); //sorts the number of likes
echo '<pre>';
    foreach ( $orderedLike as $like )
    {
        echo $like . ' '; //displays the likes
    }
echo '</pre>';

This works but then i realized that i cant sort the original array of items anymore because there are two arrays. One with numbers of likes and one with items and values(including the number of likes).

The array im ultimately trying to get into order via the like value is $item

Im not quite sure how to do this.

You can also use array_multisort() function if you want..... — Pushpendra
– Pushpendra, Commented Jul 27, 2011 at 6:06

Paul · Accepted Answer · 2011-07-27 06:23:06Z

4

You can use usort for this:

usort($item, 'cmp_by_likes');

function cmp_by_likes($a, $b){
    return $b->get_like_count()-$a->get_like_count();
}

edited Jul 27, 2011 at 6:23

answered Jul 27, 2011 at 6:04

Paul

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2 Comments

chasethesunnn Over a year ago

how would you reverse the order of the array from highest to lowest?

Paul Over a year ago

@Nils I edited my post to reverse the order. Just had to swap $a and $b in the comparison function so that they get ordered opposite.

cwallenpoole · Accepted Answer · 2011-07-27 06:10:37Z

1

You're actually not far off. You can use foreach( $arr as $key => $val ) to do that:

foreach ( $orderedLike as $key => $val )
{
    echo $item[$key]. ' '; //displays the likes
}

But maybe you're better off with usort:

// I never say this initialized.
$item = array();
// create only one array
for($i = 0; $i < $max; $i++ )
{
    // let PHP handle indexing.
    $item[] = $feed->get_item($i); //gets single items
}    
usort( $item, 'sort_by_like_count' );
// item is now sorted by get_like_count

function sort_by_like_count( $a, $b )
{
    $a = $a->get_like_count();
    $b = $b->get_like_count();
    // you can do return $a - $b here as a shortcut. I prefer being explicit as
    // 1, 0, -1 is expected more universally.
    if( $a == $b ) return 0;
    return ( $a > $b )? 1: -1;
}

answered Jul 27, 2011 at 6:10

cwallenpoole

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2 Comments

chasethesunnn Over a year ago

how would you reverse the order of the array from highest to lowest? its lowest first to highest with this setup

cwallenpoole Over a year ago

@Nils R That is as simple as changing the return to return ( $a < $b )? 1: -1;

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