Detailed explanation of PHP custom functions and array sorting examples

About sorting, generally we sort the array through the database or nosql (eg: redis) and then output it to the program for direct use, but sometimes we need to sort the array directly through PHP, and in PHP The most commonly used objects and arrays to store data are objects and arrays, but arrays are mostly processed because there are very rich built-in function libraries (in fact, objects can also be understood to a certain extent as is an array), these function libraries can help us implement certain functions to a large extent. Commonly used system functions include sort, asort, arsort, ksort, krsort, etc. Here I mainly talk about the sorting of two-dimensional arrays, two methods:

1. Use PHP’s built-in

array_multisort function to sort

<?php
  $data = array();
    $data[] = array(&#39;volume&#39; => 67, &#39;edition&#39; => 2);
    $data[] = array(&#39;volume&#39; => 86, &#39;edition&#39; => 1);
    $data[] = array(&#39;volume&#39; => 85, &#39;edition&#39; => 6);
    $data[] = array(&#39;volume&#39; => 98, &#39;edition&#39; => 2);
    $data[] = array(&#39;volume&#39; => 86, &#39;edition&#39; => 6);
    $data[] = array(&#39;volume&#39; => 67, &#39;edition&#39; => 7);
    // 取得列的列表
    foreach ($data as $key => $row)
    {
        $volume[$key]  = $row[&#39;volume&#39;];
        $edition[$key] = $row[&#39;edition&#39;];
    }
    array_multisort($volume, SORT_DESC, $edition, SORT_ASC, $data);
    print_r($data);
?>

Output results:

Array
(
    [0] => Array
        (
            [volume] => 98
            [edition] => 2
        )
    [1] => Array
        (
            [volume] => 86
            [edition] => 1
        )
    [2] => Array
        (
            [volume] => 86
            [edition] => 6
        )
    [3] => Array
        (
            [volume] => 85
            [edition] => 6
        )
    [4] => Array
        (
            [volume] => 67
            [edition] => 2
        )
    [5] => Array
        (
            [volume] => 67
            [edition] => 7
        )
)

2.

Custom function Sort 1

<?php
   $data = array();
    $data[] = array(&#39;volume&#39; => 67, &#39;edition&#39; => 2);
    $data[] = array(&#39;volume&#39; => 86, &#39;edition&#39; => 1);
    $data[] = array(&#39;volume&#39; => 85, &#39;edition&#39; => 6);
    $data[] = array(&#39;volume&#39; => 98, &#39;edition&#39; => 2);
    $data[] = array(&#39;volume&#39; => 86, &#39;edition&#39; => 6);
    $data[] = array(&#39;volume&#39; => 67, &#39;edition&#39; => 7);
    // 取得列的列表
    foreach ($data as $key => $row)
    {
        $volume[$key]  = $row[&#39;volume&#39;];
        $edition[$key] = $row[&#39;edition&#39;];
    }
    $ret = arraySort($data, &#39;volume&#39;, &#39;desc&#39;);
    print_r($ret);
    /**
     * @desc arraySort php二维数组排序 按照指定的key 对数组进行排序
     * @param array $arr 将要排序的数组
     * @param string $keys 指定排序的key
     * @param string $type 排序类型 asc | desc
     * @return array
     */
    function arraySort($arr, $keys, $type = &#39;asc&#39;) {
        $keysvalue = $new_array = array();
        foreach ($arr as $k => $v){
            $keysvalue[$k] = $v[$keys];
        }
        $type == &#39;asc&#39; ? asort($keysvalue) : arsort($keysvalue);
        reset($keysvalue);
        foreach ($keysvalue as $k => $v) {
           $new_array[$k] = $arr[$k];
        }
        return $new_array;
    }
?>

Output result:

Array
(
  [3] => Array
     (
           [volume] => 98
           [edition] => 2
        )
    [4] => Array
        (
            [volume] => 86
            [edition] => 6
        )
    [1] => Array
        (
            [volume] => 86
            [edition] => 1
        )
    [2] => Array
        (
            [volume] => 85
            [edition] => 6
        )
    [5] => Array
        (
            [volume] => 67
            [edition] => 7
        )
    [0] => Array
        (
            [volume] => 67
            [edition] => 2
        )
)

One difference between this custom function and the system function is that the custom function only supports sorting for a certain key. If To support the sorting of multiple keys, it needs to be executed multiple times; the system function array_multisort can process multiple keys at once and specify multiple sorting rules. The system function is quite powerful. It is recommended to use the system function. After all, it is implemented at the bottom of C. Here is just an example to illustrate how to sort an array through a custom function. Of course, this custom function can also be expanded to support more sorting rules. It is still used a lot in scenarios such as rankings, leaderboards, and results.

3. Custom function sorting 2

The following function sorts a given two-dimensional array according to the specified key value. Let’s look at the function first. Definition:

function array_sort($arr,$keys,$type='asc'){ 
 $keysvalue = $new_array = array();
 foreach ($arr as $k=>$v){
  $keysvalue[$k] = $v[$keys];
 }
 if($type == 'asc'){
  asort($keysvalue);
 }else{
  arsort($keysvalue);
 }
 reset($keysvalue);
 foreach ($keysvalue as $k=>$v){
  $new_array[$k] = $arr[$k];
 }
 return $new_array; 
}

It can sort a two-dimensional array according to the specified key value, or specify ascending or descending order (the default is ascending order). Usage example:

$array = array(
 array('name'=>'手机','brand'=>'诺基亚','price'=>1050),
 array('name'=>'笔记本电脑','brand'=>'lenovo','price'=>4300),
 array('name'=>'剃须刀','brand'=>'飞利浦','price'=>3100),
 array('name'=>'跑步机','brand'=>'三和松石','price'=>4900),
 array('name'=>'手表','brand'=>'卡西欧','price'=>960),
 array('name'=>'液晶电视','brand'=>'索尼','price'=>6299),
 array('name'=>'激光打印机','brand'=>'惠普','price'=>1200)
);
$ShoppingList = array_sort($array,'price');
print_r($ShoppingList);

The above is the The two-dimensional array $array is sorted from low to high according to 'price'.

The above is the detailed content of Detailed explanation of PHP custom functions and array sorting examples. For more information, please follow other related articles on the PHP Chinese website!