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<?php $color_ids = [ 'green' => [1, 2, 3], 'blue' => [4, 5], 'red' => [6], 'pink' => [7, 8, 9], 'yellow' => [10] ]; $select = ['green', 'red', 'yellow']; $result = []; foreach ($select as $color) { array_push($result, ...$color_ids[$color]); } var_export($result);

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