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<?php $array = [ [ ['2011-11-18 00:00:00' => 'C'], ['2011-11-18 00:00:00' => 'I'], ['2011-11-18 00:00:00' => 'S'] ], [ ['2011-11-22 00:00:00' => 'C'], ['2011-11-22 00:00:00' => 'S'] ] ]; var_export(array_count_values(array_map(key(...), array_merge(...$array))));
Output for 8.1.32, 8.2.0 - 8.2.29, 8.3.0 - 8.3.26, 8.4.1 - 8.4.13
array ( '2011-11-18 00:00:00' => 3, '2011-11-22 00:00:00' => 2, )
preferences:
45.86 ms | 406 KiB | 5 Q