Weighted random algorithm

random_weighted

<?php

/**
 * @param array $items
 * @param integer $multiplier
 * @return integer
 */
function random_weighted( $items, $multiplier = 1000 )
{
	$offset = 0;
	$total = array_sum( $items );
	$rand = rand( 0, $multiplier - 1 );
	foreach( $items as $item ) {
		$offset += ( $item / $total ) * $multiplier;
		if ( $rand <= $offset ) {
			return $item;
		}
	}
}