对其值为关联数组的数组进行排序

Question

我有一个数组，它的值是关联数组。我需要根据键对这个数组进行排序；

$list = array (
    array("post_id"=>"2","date"=>"2015","title"=>"title2"),
    array("post_id"=>"4","date"=>"2017","title"=>"title4"),
    array("post_id"=>"3","date"=>"2016","title"=>"title3"),
    array("post_id"=>"1","date"=>"2014","title"=>"title1")
);

例如通过 post_id 对这个数组进行排序，这意味着将该数组变为：

$list = array (
    array("post_id"=>"1","date"=>"2014","title"=>"title1"),
    array("post_id"=>"2","date"=>"2015","title"=>"title2"),
    array("post_id"=>"3","date"=>"2016","title"=>"title3"),
    array("post_id"=>"4","date"=>"2017","title"=>"title4")


);

我搜索了这个论坛，找到了这个代码：

function array_sort($array, $on, $order=SORT_ASC){

$new_array = array();
$sortable_array = array();

if (count($array) > 0) {
    foreach ($array as $k => $v) {
        if (is_array($v)) {
            foreach ($v as $k2 => $v2) {
                if ($k2 == $on) {
                    $sortable_array[$k] = $v2;
                }
            }
        } else {
            $sortable_array[$k] = $v;
        }
    }

    switch ($order) {
        case SORT_ASC:
            asort($sortable_array);
            break;
        case SORT_DESC:
            arsort($sortable_array);
            break;
    }

    foreach ($sortable_array as $k => $v) {
        $new_array[$k] = $array[$k];
    }
}

return $new_array;}

但我不明白它到底在做什么。 主题链接是： Sort PHP multi-dimensional array based on key?

Answer 1

您没有按键排序，因此您找到的示例不适合您。一个简单的usort 就可以了；

$list = array (
    array("post_id"=>"2","date"=>"2015","title"=>"title2"),
    array("post_id"=>"4","date"=>"2017","title"=>"title4"),
    array("post_id"=>"3","date"=>"2016","title"=>"title3"),
    array("post_id"=>"1","date"=>"2014","title"=>"title1")
);

function sortPosts($a, $b)
{
    if ($a['post_id'] == $b['post_id']) {
        return 0;
    }
    return ($a['post_id'] < $b['post_id']) ? -1 : 1;
}


usort($list, "sortPosts");

这会将您的 $lists 数组传递给一个函数并比较其每个值 - 您可以看到我们正在比较每个值的 ['post_id'] 值。

由于 post_id 是原始数组中的字符串，因此您可能需要将这些类型转换为整数，但请看如何进行。

Answer 2

函数 OP 问题：

• 首先通过$on 从子数组（第一个foreach）收集所有值，并通过 original_array 键$k 将其绑定到$sortable_array。喜欢$list[0]['post_id']; 收藏在：$sortable_array[0]；
• 收集完所有值后，数组将按 DESC 或 ASC（参见 switch）与 asort 进行排序，从而保持 index=>value 连接。所以$sortable_array 看起来像：在[0=>2,1=>4,2=>3,3=>1] 之前[3=>1,0=>2,2=>3,1=>4] 之后
• 所以现在对值进行了排序，并且可以在下一步中使用索引。
• 在最后一个foreach 中生成了一个新数组。 $sortable_array 中的索引 $k 用于以新顺序从 original_array 中获取子数组。

注意：这部分if (is_array($v)) 使函数行为不可预测，因为如果$v 不是子数组，则它只需要$v，否则它将从子数组中获取数据！ ！

Answer 3

您可以使用以下代码：

<?php
$list = array (
    array("post_id"=>"2","date"=>"2015","title"=>"title2"),
    array("post_id"=>"4","date"=>"2017","title"=>"title4"),
    array("post_id"=>"3","date"=>"2016","title"=>"title3"),
    array("post_id"=>"1","date"=>"2014","title"=>"title1")
);

$sorted = array_orderby($list, 'post_id', SORT_ASC);

echo "<pre>";
print_r($sorted);

function array_orderby()
{
    $args = func_get_args();
    $data = array_shift($args);
    foreach ($args as $n => $field) {
        if (is_string($field)) {
            $tmp = array();
            foreach ($data as $key => $row)
                $tmp[$key] = $row[$field];
            $args[$n] = $tmp;
            }
    }
    $args[] = &$data;
    call_user_func_array('array_multisort', $args);
    return array_pop($args);
}
?>

它将产生以下输出：

Array
(
    [0] => Array
        (
            [post_id] => 1
            [date] => 2014
            [title] => title1
        )

    [1] => Array
        (
            [post_id] => 2
            [date] => 2015
            [title] => title2
        )

    [2] => Array
        (
            [post_id] => 3
            [date] => 2016
            [title] => title3
        )

    [3] => Array
        (
            [post_id] => 4
            [date] => 2017
            [title] => title4
        )

)

Answer 4

这可能不是从该问题中选择的最佳答案。只需提取要排序的列，然后对其进行排序即可对原始列进行排序：

array_multisort(array_column($list, 'post_id'), SORT_ASC, $list);

Answer 5

最优雅的通​​常是将usort() 函数与closure 结合使用。

看看这个简单的演示：

<?php

$list = [
    ["post_id"=>"2","date"=>"2015","title"=>"title2"],
    ["post_id"=>"4","date"=>"2017","title"=>"title4"],
    ["post_id"=>"3","date"=>"2016","title"=>"title3"],
    ["post_id"=>"1","date"=>"2014","title"=>"title1"]
];

usort(
  $list,
  function($a, $b) {
    return $a['post_id'] < $b['post_id'];
  }
);
print_r($list); // First output, descending order

usort(
  $list,
  function($a, $b) {
    return $a['post_id'] > $b['post_id'];
  }
);
print_r($list); // Second output, ascending order

注意两个调用中的反向比较运算符，< 与 >...

---

这显然是：

第一个输出，降序：

Array
(
    [0] => Array
        (
            [post_id] => 4
            [date] => 2017
            [title] => title4
        )

    [1] => Array
        (
            [post_id] => 3
            [date] => 2016
            [title] => title3
        )

    [2] => Array
        (
            [post_id] => 2
            [date] => 2015
            [title] => title2
        )

    [3] => Array
        (
            [post_id] => 1
            [date] => 2014
            [title] => title1
        )

)

第二次输出，升序：

Array
(
    [0] => Array
        (
            [post_id] => 1
            [date] => 2014
            [title] => title1
        )

    [1] => Array
        (
            [post_id] => 2
            [date] => 2015
            [title] => title2
        )

    [2] => Array
        (
            [post_id] => 3
            [date] => 2016
            [title] => title3
        )

    [3] => Array
        (
            [post_id] => 4
            [date] => 2017
            [title] => title4
        )

)

Answer 6

我使用这个功能：

function aasort (&$array, $key) {
    $sorter=array();
    $ret=array();
    reset($array);
    foreach ($array as $ii => $va) {
        $sorter[$ii]=$va[$key];
    }
    asort($sorter);
    foreach ($sorter as $ii => $va) {
        $ret[$ii]=$array[$ii];
    }
    $array=$ret;
    return $array;
}

$list = array (
    array("post_id"=>"2","date"=>"2015","title"=>"title2"),
    array("post_id"=>"4","date"=>"2017","title"=>"title4"),
    array("post_id"=>"3","date"=>"2016","title"=>"title3"),
    array("post_id"=>"1","date"=>"2014","title"=>"title1")
);

$outputArray = aasort($list,"post_id");