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<?php $array = array( array("x1" => 1, "x2" => 3, "y5" => 9), array("x1" => 3, "x4" => 1, "y5" => 1), array("x1" => 1, "x8" => 5, "a5" => 2), array("x1" => 2, "x10" => 3, "b5" => 5) ); $keys = []; foreach($array as $subarr){ $keys = array_merge($keys, array_keys($subarr)); } foreach(array_unique($keys) as $item){ $res[$item] = array_sum(array_column($array, $item)); } var_dump($res);

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