Question

How to group associative array by key in PHP

Answer 1

function group_by($array) {
    foreach($array as $key => $val){
    $str = substr($key, 0, strpos($key, "_"));
    $newarr[$str][$key] = $val;
    }
    
    return $newarr;
}
    
$array = array("program_12" => 3, 
               "run_7" => 8, 
               "program_17" => 5, 
               "run_6" => 2, 
               "program_19" => 3, 
               "run_16" => 9);

$newarr = group_by($array);

var_dump($newarr);





/*
run:

array(2) {
  ["program"]=>
  array(3) {
    ["program_12"]=>
    int(3)
    ["program_17"]=>
    int(5)
    ["program_19"]=>
    int(3)
  }
  ["run"]=>
  array(3) {
    ["run_7"]=>
    int(8)
    ["run_6"]=>
    int(2)
    ["run_16"]=>
    int(9)
  }
}

*/

 

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