获取来自多维数组的值的平均值，其中日期键的匹配？ [英] Get averages of values from multidimensional array where date key's match?

问题描述

我有以下多维数组，

$ $ p $

[0] => Array
（
[place] => 1
[date] => 2013-01-01
）

[1] => ; Array
（
[place] => 2
[date] => 2013-01-02
）

[2] = >数组
（
[place] => 3
[date] => 2013-01-03
）

[3] => Array
（
[place] => 10
[date] => 2013-01-01
）

[4 ] => Array
（
[place] => 8
[date] => 2013-01-02
）

[ 5] =>数组
（
[place] => 5
[date] => 2013-01-03
）

）

如何获取每个数组的平均值atch，所以出阵数组看起来像？我已经能够做的最多的是循环数组提取日期是很容易的，但找到匹配，并获得平均值超出了我。数组
（
[0] =>数组
（
$ b（
$ b $
[place] => 5.5
[date] => 2013-01-01
）

[1] =>数组
（
[place] => 5
[date] => 2013-01-02
）

[2] => Array
（
[place] => 6.5
[date] => 2013-01-03
）

）

  $ tmp = array（）; 
 foreach（$ input为$ entry）{
 $ date = $ entry [date]; 
 $ b $ if（！array_key_exists（$ date，$ tmp））{
 $ tmp [$ date] = array（）; 
} 
 
 $ tmp [$ date] [] = $ entry [place]; 
 
 
 
 
 
 $ b现在只需要重新设置临时数组，计算平均值并生成输出你想要的格式： 
 
 
  $ averages = array（）; 
 foreach（$ tmp as $ date => $ places）{
 $ sum = array_sum（$ places）; 
 $ averages [] = array（
date=> $ date，
place=> $ sum / count（$ places）
）; 
} 
 
 print_r（$ averages）; 
  
 
I have the following multidimensional array,
Array
(
    [0] => Array
        (
            [place] => 1
            [date] => 2013-01-01
        )

    [1] => Array
        (
            [place] => 2
            [date] => 2013-01-02
        )

    [2] => Array
        (
            [place] => 3
            [date] => 2013-01-03
        )

    [3] => Array
        (
            [place] => 10
            [date] => 2013-01-01
        )

    [4] => Array
        (
            [place] => 8
            [date] => 2013-01-02
        )

    [5] => Array
        (
            [place] => 5
            [date] => 2013-01-03
        )

)
How can I get the average place each array where the dates match, so the out put array would look like? The most i've been able to do is loop over the arrays extracting the dates which is pretty easy but finding matches and getting the averages is beyond me. Thanks in advance.
Array
(
    [0] => Array
        (
            [place] => 5.5
            [date] => 2013-01-01
        )

    [1] => Array
        (
            [place] => 5
            [date] => 2013-01-02
        )

    [2] => Array
        (
            [place] => 6.5
            [date] => 2013-01-03
        )

)

解决方案
You could parse your input array into an array where the keys are the dates and the values are arrays of places for that date:
$tmp = array();
foreach( $input as $entry  ) {
    $date = $entry["date"];

    if( !array_key_exists( $date, $tmp ) ) {
        $tmp[$date] = array();
    }

    $tmp[$date][] = $entry["place"];
}
And now just go over that temporary array, calculate the averages and produce the output format you want:
$averages = array();
foreach( $tmp as $date => $places ) {
    $sum = array_sum($places);
    $averages[] = array(
        "date" => $date,
        "place" => $sum / count($places)
    );
}

print_r($averages);


                        
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