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

问题描述

我有以下数组:

$myarray = Array("2011-06-21", "2011-06-22", "2011-06-22", "2011-06-23", "2011-06-23", "2011-06-24", "2011-06-24", "2011-06-25", "2011-06-25", "2011-06-26");
var_dump($myarray);

结果:

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
)

1. 现在如何显示具有重复值的键?此处函数不应返回 ([0],[9])，因为这些值没有重复项.
2. 如何找到相同值的键，例如.对于2011-06-25"，它应该返回 [7],[8]

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;
}

显然函数名有点长；)

现在 $dups 将包含一个由重复值键控的多维数组，其中包含每个重复的键，如果您发送true"作为第二个参数，它将返回没有重复值的原始数组.

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.

或者，您可以将原始数组作为参考传递，它会在返回重复数组的同时进行相应的调整

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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