How to Efficiently Sum Column Values in Multi-Dimensional PHP Arrays?

How to Sum Columnar Values in Multi-Dimensional Arrays

In multi-dimensional arrays, summarizing values along columns is a common task. Here's how it's done, considering the challenge of dynamic associative key sets:

General-Case Solution with array_walk_recursive

Using array_walk_recursive, you can consistently summarize columns regardless of key structure:

$final = array();

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

array_column() for Exact Keys

From PHP 5.5 onwards, you can use array_column to efficiently summarize specific columns:

array_sum(array_column($input, 'gozhi')); // For 'gozhi' column

Total Sum for All Key Sets

If you want the aggregate sum of all inner arrays with matching keys (as in the desired output), use this approach:

$final = array_shift($input);

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

unset($value);

General-Case Solution with array_column

A more advanced approach using array_column involves identifying all unique keys and then summarizing:

$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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