How to implement two-dimensional array sorting in php

This article mainly introduces how to implement two-dimensional array sorting in php. Interested friends can refer to it. I hope it will be helpful to everyone.

To sort two-dimensional arrays in PHP, you can use the PHP built-in function uasort()

Example 1:

Use user-defined The comparison function sorts the values ​​in the array and maintains the index association

The callback function is as follows: Note that when the return value of the callback function is a negative number or false, it means that the first parameter of the callback function comes first , the second parameter is arranged after

$person = array(
  array('num'=>'001','id'=>6,'name'=>'zhangsan','age'=>21),
  array('num'=>'001','id'=>7,'name'=>'ahangsan','age'=>23),
  array('num'=>'003','id'=>1,'name'=>'bhangsan','age'=>23),
  array('num'=>'001','id'=>3,'name'=>'dhangsan','age'=>23),
);
//负数或者false表示第一个参数应该在前
function sort_by_name($x,$y){
  return strcasecmp($x['name'],$y['name']);
}

is used as follows:

uasort($person,'sort_by_name');

The following is a two-dimensional array sorting method for reference and interview use:

//$array 要排序的数组
//$row  排序依据列
//$type 排序类型[asc or desc]
//return 排好序的数组
function array_sort($array,$row,$type){
  $array_temp = array();
  foreach($array as $v){
    $array_temp[$v[$row]] = $v;
  }
  if($type == 'asc'){
    ksort($array_temp);
  }elseif($type='desc'){
    krsort($array_temp);
  }else{
  }
  return $array_temp;
}

Example 2:

One-dimensional array sorting can be sorted by process using some methods such as asort and ksort, which is relatively simple. How to implement sorting of two-dimensional arrays? Using array_multisort and usort can achieve

For example, the following array:

The code is as follows:

$users = array(
  array('name' => 'tom', 'age' => 20)
  , array('name' => 'anny', 'age' => 18)
  , array('name' => 'jack', 'age' => 22)
);

I hope to sort by age from small to large. The author has sorted out two methods and shared them with you.

1. Use array_multisort

Using this method will be more troublesome. You need to extract the age and store it in a one-dimensional array, and then arrange it in ascending order by age. The specific code is as follows:

The code is as follows:

$ages = array();
foreach ($users as $user) {
  $ages[] = $user['age'];
}
array_multisort($ages, SORT_ASC, $users);

After execution, $users will be a sorted array, which can be printed out to see. If you need to sort by age in ascending order first, and then by name in ascending order, the method is the same as above, that is, extract an additional name array. The final sorting method is called like this:

The code is as follows:

array_multisort($ages, SORT_ASC, $names, SORT_ASC, $users);

2. Use usort

The biggest advantage of using this method is that you can customize some more complex sorting methods. For example, sort by name length in descending order:

The code is as follows:

usort($users, function($a, $b) {
      $al = strlen($a['name']);
      $bl = strlen($b['name']);
      if ($al == $bl)
        return 0;
      return ($al > $bl) ? -1 : 1;
    });

Anonymous functions are used here, and they can be extracted separately if necessary. Among them, $a and $b can be understood as elements under the $users array. You can directly index the name value, calculate the length, and then compare the lengths.

============================================== =========================

By the way, here are a few functions of PHP sorting

sort Sort arrays Generally applicable to one-dimensional index arrays, the index will not be maintained

rsort Sort arrays in reverse order Same usage as sort

asort Sort the arrayAnd keep the index relationship to sort the values, generally suitable for one-dimensional arrays, keep the index relationship

arsort Sort the array in reverse and keep the index Relationship is consistent with asort usage

ksort sorts the array according to the key name

krsort sorts the array according to the key name in reverse order

Summary: The above is the entire content of this article, I hope it will be helpful to everyone's study.

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