sum arrays by keys

sum_arrays.php

function array_mesh() {
    // Combine multiple associative arrays and sum the values for any common keys
    // The function can accept any number of arrays as arguments
    // The values must be numeric or the summed value will be 0

    // Get the number of arguments being passed
    $numargs = func_num_args();

    // Save the arguments to an array
    $arg_list = func_get_args();

    // Create an array to hold the combined data
    $out = array();

    // Loop through each of the arguments
    for ($i = 0; $i < $numargs; $i++) {
        $in = $arg_list[$i]; // This will be equal to each array passed as an argument

        // Loop through each of the arrays passed as arguments
        foreach($in as $key => $value) {
            // If the same key exists in the $out array
            if(array_key_exists($key, $out)) {
                // Sum the values of the common key
                $sum = $in[$key] + $out[$key];
                // Add the key => value pair to array $out
                $out[$key] = $sum;
            }else{
                // Add to $out any key => value pairs in the $in array that did not have a match in $out
                $out[$key] = $in[$key];
            }
        }
    }

    return $out;
}

// Example
// $fbStats = $vkStats = array('id' => 'val')
$arSum = array_mesh($fbStats, $vkStats);

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