给定这个数组:
$inventory = array(
array("type"=>"fruit", "price"=>3.50),
array("type"=>"milk", "price"=>2.90),
array("type"=>"pork", "price"=>5.43),
);
我想按价格排序$inventory的元素,以获得:
$inventory = array(
array("type"=>"pork", "price"=>5.43),
array("type"=>"fruit", "price"=>3.50),
array("type"=>"milk", "price"=>2.90),
);
我该怎么做呢?
你是对的,你要找的函数是array_multisort()。
下面是一个直接摘自手册并根据你的情况进行调整的例子:
$price = array();
foreach ($inventory as $key => $row)
{
$price[$key] = $row['price'];
}
array_multisort($price, SORT_DESC, $inventory);
从PHP 5.5.0开始,你可以使用array_column()来代替foreach:
$price = array_column($inventory, 'price');
array_multisort($price, SORT_DESC, $inventory);
适用于PHP 7及更高版本。
/**
* A method for sorting associative arrays by a key and a direction.
* Direction can be ASC or DESC.
*
* @param $array
* @param $key
* @param $direction
* @return mixed $array
*/
function sortAssociativeArrayByKey($array, $key, $direction){
switch ($direction){
case "ASC":
usort($array, function ($first, $second) use ($key) {
return $first[$key] <=> $second[$key];
});
break;
case "DESC":
usort($array, function ($first, $second) use ($key) {
return $second[$key] <=> $first[$key];
});
break;
default:
break;
}
return $array;
}
用法:
$inventory = sortAssociativeArrayByKey($inventory, "price", "ASC");
这个函数在所有主要的PHP版本上都可以100%运行,并且在PHP5, PHP7, PHP8上都进行了测试。
function sort_my_array($array, $order_by, $order)
{
switch ($order) {
case "asc":
usort($array, function ($first, $second) use ($order_by) {
if (version_compare(PHP_VERSION, '7.0.0') >= 0) {
return $first[$order_by] <=> $second[$order_by];
} else {
$array_cmp = strcmp($first[$order_by], $second[$order_by]);
return $array_cmp ;
}
});
break;
case "desc":
usort($certificates, function ($first, $second) use ($order_by) {
if (version_compare(PHP_VERSION, '7.0.0') >= 0) {
return $first[$order_by] <=> $second[$order_by];
} else {
$array_cmp = strcmp($first[$order_by], $second[$order_by]);
return -$array_cmp ;
}
});
break;
default:
break;
}
return $array;
}
我是这样用的
<?php
$users = [
[
'username' => 'joe',
'age' => 11
],
[
'username' => 'rakoto',
'age' => 21
],
[
'username' => 'rabe',
'age' => 17
],
[
'username' => 'fy',
'age' => 19
],
];
uasort($users, function ($item, $compare) {
return $item['username'] >= $compare['username'];
});
var_dump($users);
从PHP 7.4开始,你可以使用arrow函数:
usort(
$inventory,
fn(array $a, array $b): int => $b['price'] <=> $a['price']
);
代码(演示):
$inventory = [
['type' => 'fruit', 'price' => 3.50],
['type' => 'milk', 'price' => 2.90],
['type' => 'pork', 'price' => 5.43],
];
usort(
$inventory,
fn(array $a, array $b): int => $b['price'] <=> $a['price']
);
print_r($inventory);
(浓缩)输出:
Array
(
[0] => Array ([type] => pork, [price] => 5.43)
[1] => Array ([type] => fruit, [price] => 3.5)
[2] => Array ([type] => milk, [price] => 2.9)
)
在php中,根据给定key的值对关联数组进行排序:
通过使用usort (http://php.net/usort),我们可以按升序和降序对数组进行排序。只是我们需要创建一个函数,并将其作为参数传递给usort。按照下面的例子,使用大于表示升序,如果我们通过小于条件,那么它将按降序排序。
例子:
$array = array(
array('price'=>'1000.50','product'=>'test1'),
array('price'=>'8800.50','product'=>'test2'),
array('price'=>'200.0','product'=>'test3')
);
function cmp($a, $b) {
return $a['price'] > $b['price'];
}
usort($array, "cmp");
print_r($array);
输出:
Array
(
[0] => Array
(
[price] => 200.0
[product] => test3
)
[1] => Array
(
[price] => 1000.50
[product] => test1
)
[2] => Array
(
[price] => 8800.50
[product] => test2
)
)