php 二维数组自定义排序

eg1：只根据一个规则进行排序，比如我下面的数组是一组满减折扣的信息，我要按照满减的金额从小到大排序

代码：

<?php

$arr =[
    ["amount"=> 60,"discount"=> 35],
    ["amount"=> 20,"discount"=> 10],
    ["amount"=> 5,"discount"=> 3]
];

$column = array_column($arr,'amount');

array_multisort($column,SORT_ASC,$arr);
print_r($column);
print_r($arr);

?>

输出：

Array
(
    [0] => 5
    [1] => 20
    [2] => 60
)
Array
(
    [0] => Array
        (
            [amount] => 5
            [discount] => 3
        )

    [1] => Array
        (
            [amount] => 20
            [discount] => 10
        )

    [2] => Array
        (
            [amount] => 60
            [discount] => 35
        )

)

eg2：有时候需要对一个二维数组进行排序，自定义对应的排序规则，比如对一个班级里面的同学，先按身高降序排序，身高相同的，再按体重降序排序。。。

代码：

<?php
$array = [
    ["id" => "1", "name" => "a", "age" => "19",],
    ["id" => "2", "name" => "b", "age" => "39",],
    ["id" => "3", "name" => "c", "age" => "9",],
    ["id" => "4", "name" => "d", "age" => "1",],
    ["id" => "5", "name" => "e", "age" => "88",],
    ["id" => "6", "name" => "f", "age" => "65",],
    ["id" => "7", "name" => "g", "age" => "19",],
];

array_multisort(array_column($array,"age"),SORT_DESC,array_column($array,"id"),SORT_DESC,$array);
print_r($array);
?>

上面这个二维数组，先按年龄（age）降序排序，如果年龄（age）相同的话，再按 id 降序排序

输出：

Array
(
    [0] => Array
        (
            [id] => 5
            [name] => e
            [age] => 88
        )

    [1] => Array
        (
            [id] => 6
            [name] => f
            [age] => 65
        )

    [2] => Array
        (
            [id] => 2
            [name] => b
            [age] => 39
        )

    [3] => Array
        (
            [id] => 7
            [name] => g
            [age] => 19
        )

    [4] => Array
        (
            [id] => 1
            [name] => a
            [age] => 19
        )

    [5] => Array
        (
            [id] => 3
            [name] => c
            [age] => 9
        )

    [6] => Array
        (
            [id] => 4
            [name] => d
            [age] => 1
        )

)

如果遇到下面的PHP警告，就是你拿来比较的标志的数组大小跟待排序的数组大小不一致，可以把 array_multisort 里面的数组都打印出来看下大小是否一致

PS：PHP Warning : array_multisort(): Array sizes are inconsistent