Group 2D array data using column values ​​to generate 3D array

Question

I have a multidimensional array that I want to group based on the values ​​in a specific column.

I want to group based on level, but I don’t know the value of level in advance. So, I can't say while $i < 7 like in the for loop, because I don't know that 7 is the level key of the maximum value, and even if I knew I'm not sure I'd need to do that.

[
    ['cust' => 'XT8900', 'type' => 'standard', 'level' => 1],
    ['cust' => 'XT8944', 'type' => 'standard', 'level' => 1],
    ['cust' => 'XT8922', 'type' => 'premier', 'level' => 3],
    ['cust' => 'XT8816', 'type' => 'permier', 'level' => 3],
    ['cust' => 'XT7434', 'type' => 'standard', 'level' => 7],
]

Desired result:

Array (

   [1] => Array (
          [0] => Array (
                    [cust] => XT8900
                    [type] => standard
                    )
          [1] => Array (
                    [cust] => XT8944
                    [type] => standard
                    )
          )

   [3] => Array (
          [2] => Array (
                 [cust] => XT8922
                 [type] => premier
                 )

          [3] => Array (
                 [cust] => XT8816
                 [type] => permier
                 )
          )

   [7] => Array (
          [4] => Array (
                 [cust] => XT7434
                 [type] => standard
                 )
          )
)

Answer 1

The best approach is if you have control over building the initial array, then just set it up at the beginning when adding entries.

If there is no control, a temporary array is constructed for sorting:

foreach ($input_arr as $key => &$entry) {
    $level_arr[$entry['level']][$key] = $entry;
}

This gives you the form you want, with all the references together.

If possible, initially build the array like this.

Answer 2

First, you need to group them by level

Use foreach to loop through the array, check if the level is the same as the previous item, then group it with that array

$templevel=0;   

  $newkey=0;

  $grouparr[$templevel]="";

  foreach ($items as $key => $val) {
   if ($templevel==$val['level']){
     $grouparr[$templevel][$newkey]=$val;
   } else {
     $grouparr[$val['level']][$newkey]=$val;
   }
     $newkey++;       
  }
print($grouparr);

---

print($grouparr);The output will be displayed in the format you want

You can also try

print($grouparr[7]);

will be displayed

[7] => Array (
      [4] => Array (
             [cust] => XT7434
             [type] => standard
             )
      )

or

print($grouparr[3]);

will be displayed

[3] => Array (
      [2] => Array (
             [cust] => XT8922
             [type] => premier
             )

      [3] => Array (
             [cust] => XT8816
             [type] => permier
             )
      )