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<?php $array = [ ['toxic', 'irritant', 'flammable'], ['toxic', 'irritant'], ['toxic'], ]; var_export( array_count_values( array_merge(...$array) ) );
Output for 8.1.0 - 8.1.28, 8.2.0 - 8.2.19, 8.3.0 - 8.3.7
array ( 'toxic' => 3, 'irritant' => 2, 'flammable' => 1, )
preferences:
46.41 ms | 402 KiB | 62 Q