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<?php function transformQuestionnaire($arr) { $new_arr = array(); foreach ($arr as $array){ $key = reset($array); $val = end($array); if (!in_array($key, array_keys($new_arr))){ //not a double $new_arr[$key] = $val; } else { //Append it to the existing value $new_arr[$key] .= '|' . $val; } } return $new_arr; } $input = array( array("one", "potato"), array("two", "fries"), array("one", "ketchup"), array("two", "steak")); print(var_dump(transformQuestionnaire($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, 5.5.24 - 5.5.35, 5.6.8 - 5.6.28, 7.0.0 - 7.0.20, 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 - 8.1.28, 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
array(2) { ["one"]=> string(14) "potato|ketchup" ["two"]=> string(11) "fries|steak" }

preferences:
252.53 ms | 406 KiB | 343 Q