+/**
+ * Given an array of non-normalised probabilities, this function will select
+ * an element and return the appropriate key
+ *
+ * @param $weights array
+ *
+ * @return int|string
+ */
+function wfPickRandom( $weights ){
+ if ( !is_array( $weights ) || count( $weights ) == 0 ) {
+ return false;
+ }
+
+ $sum = array_sum( $weights );
+ if ( $sum == 0 ) {
+ # No loads on any of them
+ # In previous versions, this triggered an unweighted random selection,
+ # but this feature has been removed as of April 2006 to allow for strict
+ # separation of query groups.
+ return false;
+ }
+ $max = mt_getrandmax();
+ $rand = mt_rand( 0, $max ) / $max * $sum;
+
+ $sum = 0;
+ foreach ( $weights as $i => $w ) {
+ $sum += $w;
+ if ( $sum >= $rand ) {
+ break;
+ }
+ }
+ return $i;
+}
+