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<?php $array = [ 'for-juniors' => 'product_category', 'for-men' => 'product_category', 'coats' => 'product_category', 'for-women' => 'product_category', '7-diamonds' => 'brand' ]; $grouped = []; foreach ($array as $grouped[$group][] => $group); var_export($grouped);
Output for 7.4.0 - 7.4.33, 8.0.1 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.27, 8.4.1 - 8.4.14
array ( 'product_category' => array ( 0 => 'for-juniors', 1 => 'for-men', 2 => 'coats', 3 => 'for-women', ), 'brand' => array ( 0 => '7-diamonds', ), )

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135.16 ms | 407 KiB | 5 Q