How to Sum Columnar Values in Multi-Dimensional PHP Arrays?

Adding Columnar Values in Multi-Dimensional Arrays

You're aiming to sum the values associated with specific keys in a multi-dimensional array with varying key sets. Consider the following input:

Array
(
    [0] => Array
        (
            [gozhi] => 2
            [uzorong] => 1
            [ngangla] => 4
            [langthel] => 5
        )

    [1] => Array
        (
            [gozhi] => 5
            [uzorong] => 0
            [ngangla] => 3
            [langthel] => 2
        )

    [2] => Array
        (
            [gozhi] => 3
            [uzorong] => 0
            [ngangla] => 1
            [langthel] => 3
        )
)

The desired outcome is:

Array
(
    [gozhi] => 10
    [uzorong] => 1
    [ngangla] => 8
    [langthel] => 10
)

To achieve this, consider the following approaches:

array_walk_recursive()

For a general-case solution, use array_walk_recursive():

$final = array();

array_walk_recursive($input, function($item, $key) use (&$final){
    $final[$key] = isset($final[$key]) ?  $item + $final[$key] : $item;
});

array_column()

For specific keys (e.g., "gozhi"), use array_column() (available since PHP 5.5):

array_sum(array_column($input, 'gozhi'));

For Arrays with Identical Keys

If all inner arrays have the same keys:

$final = array_shift($input);

foreach ($final as $key => &$value){
   $value += array_sum(array_column($input, $key));
}    

unset($value);

General-Case Solution with array_column()

Get all unique keys and then sum for each:

$final = array();

foreach($input as $value)
    $final = array_merge($final, $value);

foreach($final as $key => &$value)
    $value = array_sum(array_column($input, $key));

unset($value);

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