Online PHP editor | refs for WtDNq

<?php $a = ['a1','a2','a3','a4']; $b = ['b1','b2','b3','b4']; $c = ['c1','c2','c3','c4']; $all = [ $a, $b, $c ]; $result = []; for( $i=0; $i<count( $a ); $i++ ) { for( $j=0; $j<count( $all ); $j++ ) { $result[] = $all[ 3*(($i+$j*2)%3>0)-(($i+$j*2)%3) ][ $i ]; } } print_r($result);