Filter part of multidimensional array - php

Question

I would like to filter part of a multidimensional array. I have used the array_filter function. When I print the filtered data, it shows correctly, but I can't seem to save the data back to the array.
Here is the multidimensional array (called $posted_product_details) beforehand, containing the internal array ([data]) which I would like filter:
Array
(
[column_1] => Array
(
[name] => Colour
[data] => Array
(
[0] => Blue
[1] => Green
[2] => Red
[3] => Yellow
[4] =>
[5] =>
[6] =>
[7] =>
[8] =>
[9] =>
)
)
[column_2] => Array
(
[name] => Pack QTY
[data] => Array
(
[0] => 3
[1] => 3
[2] => 3
[3] => 3
[4] =>
[5] =>
[6] =>
[7] =>
[8] =>
[9] =>
)
)
[column_3] => Array
(
[name] => Product Code
[data] => Array
(
[0] => 65030
[1] => 65029
[2] => 65028
[3] => 65031
[4] =>
[5] =>
[6] =>
[7] =>
[8] =>
[9] =>
)
)
[column_4] => Array
(
[name] => Barcode
[data] => Array
(
[0] => 5099570650307
[1] => 5099570650291
[2] => 5099570650284
[3] => 5099570650314
[4] =>
[5] =>
[6] =>
[7] =>
[8] =>
[9] =>
)
)
[column_5] => Array
(
[name] =>
[data] => Array
(
[0] =>
[1] =>
[2] =>
[3] =>
[4] =>
[5] =>
[6] =>
[7] =>
[8] =>
[9] =>
)
)
)
Here I attempt to loop through the array and filter the data:
foreach ($posted_product_details as $column => $info) {
$name = $info['name'];
$data = $info['data'];
$info['data'] = array_filter($data);
}
However, upon printing the array afterward, the array has not changed.

Answer 1

Pass the value by reference to modify the original array:
foreach ($posted_product_details as $column => & $info) {
$name = $info['name'];
$data = $info['data'];
$info['data'] = array_filter($data);
}
This will correctly filter the data part of your array. However, if you need to filter out deeper elements, you'll have to use a recursive function, such as this one.
Demo!

Answer 2

The foreach construct makes a copy of each piece of the array as you iterate over it. You have to explicitly call the original array to edit it:
$posted_product_details[$column]['data'] = array_filter($data);