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<?php $data =[1, 63, 1, 2, 2, 'a', 'b', '1', 'b']; $data = array_filter($data, function ($value) use ($data) { return !(array_count_values($data)[$value] > 1); }); print_r($data);

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49.24 ms | 402 KiB | 5 Q