Mistake key did not do what I thought. A patch.
function array_bucket($array,$bucket_size)// bucket filter
{
 if (!is_array($array)) return false;
 $buckets=array_chunk($array,$bucket_size);// chop up array into bucket size units
 $I=0;
 foreach ($buckets as $bucket)
 {
 $new_array[$I++]=array_sum($bucket)/count($bucket);
 }
 return $new_array;// return new array
}