array_input is the array which can be dynamic up to any level, I want to convert input array into the array_output format using php

Input Array : Input array is like below and level in it can be dynamic up to any level,

$array_input = [
            0 => ["level" => "L1", "points" => 1000], 
            1 => ["level" => "L1", "points" => 5000],
            2 => ["level" =>"L2 ", "points" => 3000], 
            3 => ["level" => "L3", "points" => 4000], 
            4 => ["level" => "L3", "points" => 6000], 
            5 => ["level" => "L2", "points" => 4000], 
            6 => ["level" => "L2", "points" => 5000], 
            7 => ["level" => "L2", "points" => 5000], 
            8 => ["level" => "L1", "points" => 6000], 
            9 => ["level" => "L1", "points" => 2000]
];

OUTPUT ARRAY: Output array should be like below, I tried using 2 foreach loop and accessing previous Level and compare it to next Level. But it is creating problem where Level is more than 2 times.

$array_output = [
    0 => [
        0 => ["level" => "L1", "points" => 1000], 
        1 => ["level" => "L1", "points" => 5000]
    ], 
    1 => [
        0 => ["level" => "L2", "points" => 3000]
    ], 
    2 => [
        0 => ["level" => "L3", "points" => 4000], 
        1 => ["level" => "L3", "points" => 6000]
    ], 
    3 => [
        0 => ["level" => "L2", "points" => 4000], 
        1 => ["level" => "L2", "points" => 5000], 
        2 => ["level" => "L2", "points" => 5000]
    ], 
    4 => [
        0 => ["level" => "L1", "points" => 6000], 
        1 => ["level" => "L1", "points" => 2000]
    ]
];

This is the code i tried but it’s not giving result what i want:

$opArr = [];
$i=1;
$justArr = [];

$pre = $array_input[0]['level'];
$firstArr = $array_input[0];


for($i; $i<count($array_input); $i++){ // 0
        
        foreach($array_input[$i] as $key => $value){
            if($key == 'level'){
                $level = $value;     
            }      
            
        }
        if($pre == $level ){
            $opArr[] = $firstArr; 
            $opArr[] = $array_input[$i];
        }

        $pre = $array_input[$i]['level'];
        $firstArr = $array_input[$i];
        
}


echo "<pre>";
echo "OpArr:";
print_r($opArr);
echo "<pre>";

Answer

You may give this a try. See comments for step-by-step explanation. Outputs:

array(5) {
  [0]=>
  array(2) {
    [0]=>
    array(2) {
      ["level"]=>
      string(2) "L1"
      ["points"]=>
      int(1000)
    }
    [1]=>
    array(2) {
      ["level"]=>
      string(2) "L1"
      ["points"]=>
      int(5000)
    }
  }
  [1]=>
  array(1) {
    [0]=>
    array(2) {
      ["level"]=>
      string(2) "L2"
      ["points"]=>
      int(3000)
    }
  }
  [2]=>
  array(2) {
    [0]=>
    array(2) {
      ["level"]=>
      string(2) "L3"
      ["points"]=>
      int(4000)
    }
    [1]=>
    array(2) {
      ["level"]=>
      string(2) "L3"
      ["points"]=>
      int(6000)
    }
  }
  [3]=>
  array(3) {
    [0]=>
    array(2) {
      ["level"]=>
      string(2) "L2"
      ["points"]=>
      int(4000)
    }
    [1]=>
    array(2) {
      ["level"]=>
      string(2) "L2"
      ["points"]=>
      int(5000)
    }
    [2]=>
    array(2) {
      ["level"]=>
      string(2) "L2"
      ["points"]=>
      int(5000)
    }
  }
  [4]=>
  array(2) {
    [0]=>
    array(2) {
      ["level"]=>
      string(2) "L1"
      ["points"]=>
      int(6000)
    }
    [1]=>
    array(2) {
      ["level"]=>
      string(2) "L1"
      ["points"]=>
      int(2000)
    }
  }
}

Code:

<?php

// Your input array.
$array_input = [
            0 => ["level" => "L1", "points" => 1000], 
            1 => ["level" => "L1", "points" => 5000],
            2 => ["level" =>"L2", "points" => 3000], 
            3 => ["level" => "L3", "points" => 4000], 
            4 => ["level" => "L3", "points" => 6000], 
            5 => ["level" => "L2", "points" => 4000], 
            6 => ["level" => "L2", "points" => 5000], 
            7 => ["level" => "L2", "points" => 5000], 
            8 => ["level" => "L1", "points" => 6000], 
            9 => ["level" => "L1", "points" => 2000]
];

$output = [];
// Keep track of last group key seen so we can
// create a new child array on every boundary.
$lastGroupKey = $array_input[0]['level'];

// Output array.
$grouped = [];

// Loop over every input element.
foreach ($array_input as $input)
{
    // Grouping on 'level' value, which we'll use as a 'key'.
    $groupKey = $input['level'];

    // If current key is not the last one seen, then this is a
    // boundary. Push the current group onto the output
    // and start afresh.
    if ($groupKey !== $lastGroupKey)
    {
        $output[] = $grouped;
        $grouped = [];
    }

    // Record each row.
    $grouped[] = $input;

    // Update last key seen.
    $lastGroupKey = $groupKey;
}

// The end of the array is the final boundary.
// Record trailing group.
$output[] = $grouped;

var_dump($output);
/*
array(5) {
  [0]=>
  array(2) {
    [0]=>
    array(2) {
      ["level"]=>
      string(2) "L1"
      ["points"]=>
      int(1000)
    }
    [1]=>
    array(2) {
      ["level"]=>
      string(2) "L1"
      ["points"]=>
      int(5000)
    }
  }
  [1]=>
  array(1) {
    [0]=>
    array(2) {
      ["level"]=>
      string(2) "L2"
      ["points"]=>
      int(3000)
    }
  }
  [2]=>
  array(2) {
    [0]=>
    array(2) {
      ["level"]=>
      string(2) "L3"
      ["points"]=>
      int(4000)
    }
    [1]=>
    array(2) {
      ["level"]=>
      string(2) "L3"
      ["points"]=>
      int(6000)
    }
  }
  [3]=>
  array(3) {
    [0]=>
    array(2) {
      ["level"]=>
      string(2) "L2"
      ["points"]=>
      int(4000)
    }
    [1]=>
    array(2) {
      ["level"]=>
      string(2) "L2"
      ["points"]=>
      int(5000)
    }
    [2]=>
    array(2) {
      ["level"]=>
      string(2) "L2"
      ["points"]=>
      int(5000)
    }
  }
  [4]=>
  array(2) {
    [0]=>
    array(2) {
      ["level"]=>
      string(2) "L1"
      ["points"]=>
      int(6000)
    }
    [1]=>
    array(2) {
      ["level"]=>
      string(2) "L1"
      ["points"]=>
      int(2000)
    }
  }
}
*/