获取数组中重复值的键 [英] Get the keys for duplicate values in an array

问题描述

如果我的数组是

Array ( [0] => 2011-06-21 [1] => 2011-06-22 [2] => 2011-06-22 [3] => 2011-06-23 [4] =>
2011-06-23 [5] => 2011-06-24 [6] => 2011-06-24 [7] => 2011-06-25 [8] => 2011-06-25 [9] 
=> 2011-06-26 [10] => 2011-06-26 [11] => 2011-06-27 [12] => 2011-06-27 [13] => 2011-06-  
28 [14] => 2011-06-29 [15] => 2011-06-29 [16] => 2011-06-30 [17] => 2011-06-30 [18] => 
2011-07-01 [19] => 2011-07-01 [20] => 2011-07-02 [21] => 2011-07-02 [22] => 2011-07-03 
[23] => 2011-07-03 [24] => 2011-07-04 [25] => 2011-07-04 [26] => 2011-07-05 [27] => 2011-
07-05 [28] => 2011-07-06 [29] => 2011-07-06 [30] => 2011-07-07 [31] => 2011-07-07 ) 

1. 用重复的值显示键？
   例如这里的函数不应该返回（[0]，[13]），因为没有重复的值。


2. 如何找到该值的键，例如2011-06 -29应该返回[15]，[16]

推荐答案

function get_keys_for_duplicate_values($my_arr, $clean = false) {
    if ($clean) {
        return array_unique($my_arr);
    }

    $dups = $new_arr = array();
    foreach ($my_arr as $key => $val) {
      if (!isset($new_arr[$val])) {
         $new_arr[$val] = $key;
      } else {
        if (isset($dups[$val])) {
           $dups[$val][] = $key;
        } else {
           $dups[$val] = array($key);
           // Comment out the previous line, and uncomment the following line to
           // include the initial key in the dups array.
           // $dups[$val] = array($new_arr[$val], $key);
        }
      }
    }
    return $dups;
}

显然功能名称有点长;）

obviously the function name is a bit long;)

现在，$ dups将包含由重复值键入的多维数组，其中包含每个重复的键，如果发送true作为第二个参数，它将返回原始数组，而不返回重复的值。

Now $dups will contain a multidimensional array keyed by the duplicate value, containing each key that was a duplicate, and if you send "true" as your second argument it will return the original array without the duplicate values.

另外，您可以将原始数组作为参考传递，并相应调整它，同时返回您的重复数组

Alternately you could pass the original array as a reference and it would adjust it accordingly while returning your duplicate array

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