<?php
$string = '1-350,9-390.99';
// first, split the string into an array of pairs
$output = explode(',', $string);
function split_pairs ($str) {
return explode('-', $str, 2);
}
$output = array_map(split_pairs, $output);
// then transpose it to get two arrays, one for keys and one for values
array_unshift($output, null);
$output = call_user_func_array(array_map, $output);
// and finally combine them into one
$output = array_combine($output[0], $output[1]);
var_export($output);