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<?php $array = [ 1 => [ 1 => [ 'anna', 'alice' ], 2 => [ 'bob', 'bartold' ] ], 2 => [ 1 => [ 'carol' ], 2 => [ 'david' ] ] ]; $result = []; $prevKey = 0; array_walk_recursive($array, function ($value, $key) use (&$result, &$prevKey) { $prevKey = $key; if (!is_array($value)) { echo "{$prevKey} <br /> -- {$value} <br />"; } }); var_dump($result);

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