3v4l.org

run code in 300+ PHP versions simultaneously
<?php $sample = array('a.col1','a.col2','b.col1','c.col1','c.col2','d.col5'); $new = []; foreach($sample as $value){ $arr = explode(".", $value); if(array_key_exists($arr[0],$new)){ array_push($new[$arr[0]], $arr[1]); }else{; $new[$arr[0]][] = $arr[1]; } } print_r($new );
Output for 7.1.25 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33, 8.0.0 - 8.0.30, 8.1.0 - 8.1.33, 8.2.0 - 8.2.29, 8.3.0 - 8.3.25, 8.4.1 - 8.4.12
Array ( [a] => Array ( [0] => col1 [1] => col2 ) [b] => Array ( [0] => col1 ) [c] => Array ( [0] => col1 [1] => col2 ) [d] => Array ( [0] => col5 ) )
preferences:
139.8 ms | 408 KiB | 5 Q