Question

what is the easiest way to change this array to 1D array, i can do that using for loop or foreach, but i’m curious to check if there is an easier way. THANKS

Array
(
    [0] => Array
        (
            [id] => 1
        )

    [1] => Array
        (
            [id] => 2
        )

    [2] => Array
        (
            [id] => 3
        )
)

Answer 1

$output_ar = array_map('array_shift', $input_ar);

The array_shift() function grabs the first key/val pair out of an array and returns the value, so applying it to each of the arrays in your top-level array, and combining the results, will result in a 1-d list of the id’s.

If your arrays actually have more info than just the id field in them, then you’d probably want to define a function that specifically pulls out whatever field(s) you want and returns those, and then use that function with array_map.