Question

I have a multi dimentional php array like this :

where the column “b” has 2 possible values ( x, y) and column “v” has 2 possible values ( t,f )

Array
(
[0] => Array
    (
        [a] => 6
        [b] => x
        [c] => t
    )

[1] => Array
    (
        [a] => 4
        [b] => x
        [c] => t
    )
[2] => Array
    (
        [a] => 6
        [b] => y
        [c] => f
    )

I want to rearrange the columns so that they are structured by values , in the following way.

My Question is, is there a smart way to do this using some native php functions , without looping through everything

Array(
    [value of b=x] => Array(
        [value of c=t] => Array( all ids in the array)
        [value of c=f] => Array( all ids in the array)
     )
    [value of b=y] => Array(
        [value of c=t] => Array( all ids in the array)
        [value of c=f] => Array( all ids in the array)
     )

  )         

Answer 1

I assume that by all ids in the array you mean “all the a column values in the array”. In which case, this is what you want:

$result = array();

array_walk($array, function($val, $key) use (&$result) {
  $result[$val['b']][$val['c']][] = $val['a'];
});

print_r($result);

If by ids you mean the outer array indices, simply change $val['a'] to $key in the above code.