Example of specifying multi-field sorting for PHP multidimensional arrays

This article mainly introduces examples of specifying multi-field sorting for PHP multi-dimensional arrays. It has a certain reference value. Now I share it with you. Friends in need can refer to it.

Introducing the array_multisort method

array_multisort — Sort multiple arrays or multidimensional arrays. The instructions in the PHP manual are as follows:

Copy code The code is as follows:

bool array_multisort ( array &$arr [, mixed $arg = SORT_ASC [, mixed $arg = SORT_REGULAR [, mixed $... ]]] )

Parameters

arr
An array to be sorted.

#arg
Each of the following parameters can be another array or a sorting flag option parameter for the previous array: SORT_ASC, SORT_DESC, SORT_REGULAR, SORT_NUMERIC, SORT_STRING.
…
Additional arg's.

First implement the sorting of one field of the specified multi-dimensional array

Here it is required to sort the array according to one of the fields. The array assumptions are as follows:

  $array = array(
      0=>array('id'=>8,'name'=>'Tom'),
      1=>array('id'=>9,'name'=>'Peter'),
      2=>array('id'=>5,'name'=>'Jack')
  );

We need to sort according to the id value of the two-dimensional array. The converted array format is as follows:

  $array = array(
      0=>array('id'=>5,'name'=>'Jack')
      1=>array('id'=>8,'name'=>'Tom'),
      2=>array('id'=>9,'name'=>'Peter')
  );

To complete the above conversion, you need to use the array_multisort function introduced above, as follows:

  function sortArrByOneField(&$array, $field, $desc = false){
    $fieldArr = array();
    foreach ($array as $k => $v) {
     $fieldArr[$k] = $v[$field];
    }
    $sort = $desc == false ? SORT_ASC : SORT_DESC;
    array_multisort($fieldArr, $sort, $array);
  }

By The $field of each array in the sorted array is stored in a one-bit array fieldArr and participates in sorting in the incoming array_multisort. The value of the field array is as follows:

array(0=>8,1=>9,2=>5)

After passing in array_multisort, it is equivalent to sorting the $field one-dimensional array, and then rebuilding it based on the sorted key The incoming array to be sorted.

Implementing sorting of multi-dimensional arrays by specifying multiple fields

The above example explains how to implement sorting of multi-dimensional arrays by specifying one field, but if you want How to think about specifying multiple fields to sort an array?
How many fields are there? 2, 3 or more, so this uncertain factor needs to be eliminated.

Let’s first look at the 2 solutions for specifying 2 fields for sorting:

  $arr = array(
    '0' => array(
      'id' => 3,
      'age' => 27 
    ),
    '1' => array(
      'id' => 5,
      'age' => 50
    )，
    '2' => array(
      'id' => 4,
      'age' => 44
    ),
    '3' => array(
      'id' => 3,
      'age' => 78
    ) 
  );
  foreach ( $arr as $key => $row ){
    $id[$key] = $row ['id'];
    $age[$key] = $row ['age'];
  }
  array_multisort($id, SORT_ASC, $age, SORT_DESC, $arr);
  print_r($arr);
  //result:Array([0]=>Array(['id']=>3 ['age']=>78) [1]=>Array(['id']=>3 ['age']=>27) [2]=>Array(['id']=>4 ['age']=>44) [3]=>Array(['id']=>5 ['age']=>50))

Refactor the above code, just use php The func_get_args function in can dynamically obtain the incoming value, which can solve the problem of uncertain number of multiple fields. The implementation is as follows:

  $array1 = array(
        0=>array('id'=>8,'name'=>'Apple','age'=> 18),
        1=>array('id'=>8,'name'=>'Bed','age'=>17),
        2=>array('id'=>5,'name'=>'Cos','age'=>16),
        3=>array('id'=>5,'name'=>'Cos','age'=>14)
  );
  function sortArrByManyField(){
    $args = func_get_args();
    if(empty($args)){
      return null;
    }
    $arr = array_shift($args);
    if(!is_array($arr)){
      throw new Exception("第一个参数不为数组");
    }
    foreach($args as $key => $field){
      if(is_string($field)){
        $temp = array();
        foreach($arr as $index=> $val){
          $temp[$index] = $val[$field];
        }
        $args[$key] = $temp;
      }
    }
    $args[] = &$arr;//引用值
    call_user_func_array('array_multisort',$args);
    return array_pop($args);
  }
  $arr = sortArrByManyField($array1,'id',SORT_ASC,'name',SORT_ASC,'age',SORT_DESC);
  print_r($arr);

The running result is as follows:

    array(4) {
      [0]=>array(3) {
            ["id"]=>int(5)
            ["name"]=>string(3) "Cos"
            ["age"]=>int(16)
          }
      [1]=>array(3) {
            ["id"]=>int(5)
            ["name"]=>string(3) "Cos"
            ["age"]=>int(14)
          }
      [2]=>array(3) {
            ["id"]=>int(8)
            ["name"]=>string(5) "Apple"
            ["age"]=>int(18)
          }
      [3]=>array(3) {
            ["id"]=>int(8)
            ["name"]=>string(3) "Bed"
            ["age"]=>int(17)
      }
    }

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