- var_dump: documentation ( source)
- array_values: documentation ( source)
- json_encode: documentation ( source)
<?php
$open_rates = [];
$open_rates["x"]["0"] = "Sun";
$open_rates["x"]["2"] = "Mon";
var_dump(json_encode($open_rates));
$open_rates["x"] = array_values($open_rates["x"]);
var_dump(json_encode($open_rates));