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<?php function transformQuestionnaire($arr) { $new_arr = array(); foreach ($arr as $array){ if (!in_array($array[0], $new_arr)){ //not a double $new_arr[$array[0]] = $array[1]; } else { //Append it to the existing value $new_arr[$array[0]] = $new_arr[$array[0]] . '|' . $array[1]; } } return $new_arr; } $input = array( 1 => array("one", "potato"), 2 => array("two", "fries"), 3 => array("one", "ketchup"), ); print(var_dump(transformQuestionnaire($input))); ?>
Output for 4.3.0 - 4.3.11, 4.4.0 - 4.4.9, 5.0.0 - 5.0.5, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17, 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.27, 8.2.0 - 8.2.17, 8.3.0 - 8.3.4
array(2) { ["one"]=> string(7) "ketchup" ["two"]=> string(5) "fries" }

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291.99 ms | 405 KiB | 456 Q