Tryit Editor v2.3

PHP Source:

<!DOCTYPE html>
<html>
<body>

<?php
$a1=array("a"=>"red","b"=>"green","c"=>"blue","d"=>"yellow");
$a2=array("a"=>"purple","b"=>"orange");
print_r(array_splice($a1,0,2,$a2));
?>

</body>
</html>