查找所有具有相同值的数组键

2022-01-10 00:00:00 arrays duplicates php

当值未知时，是否有更简单的方法来获取具有相同值的所有数组键.

Is there a simpler way to get all array keys that has same value, when the value is unknown.

array_unique 的问题 是它返回唯一数组，因此找不到唯一值.

The problem with array_unique is that it returns the unique array and thus it doesn't find unique values.

即例如从这个数组中:

Array (
  [a]=>1000
  [b]=>1
  [c]=>1000
)

我想要这个

Array (
  [a]=>1000
  [c]=>1000
)

另一种解决方法是，如果我能找到 lonely 值，然后找到它们的键，然后使用 array_diff

Another way around this is, if I could find the lonely values, and then their keys, and then use array_diff

这是我目前得到的，看起来很糟糕:

This is what I've got so far, looks awful:

$a = array( 'a' => 1000, 'b' => 1, 'c' => 1000 );
$b = array_flip( array_count_values( $a ) );
krsort( $b );
$final = array_keys( $a, array_shift( $b ) );

更新
使用 Paulo Freites 的答案作为代码库，我可以让它工作起来非常容易、可维护且易于使用……通过将过滤用作静态类方法，我可以通过调用 ClassName::get_duplicates($array_to_filter)

private static $counts = null;

private static function filter_duplicates ($value) {
    return self::$counts[ $value ] > 1;
}

public static function get_duplicates ($array) {
    self::$counts = array_count_values( $array );
    return array_filter( $array, 'ClassName::filter_duplicates' );
}

推荐答案

利用闭包获得更直接的解决方案:

Taking advantage of closures for a more straightforward solution:

$array = array('a' => 1000, 'b' => 1, 'c' => 1000);
$counts = array_count_values($array);
$filtered = array_filter($array, function ($value) use ($counts) {
    return $counts[$value] > 1;
});
var_dump($filtered);

这给了我以下信息:

array(2) {
  ["a"]=>
  int(1000)
  ["c"]=>
  int(1000)
}

演示:https://eval.in/67526

就是这样！:)

更新:向后兼容的解决方案

$array = array('a' => 1000, 'b' => 1, 'c' => 1000);
$counts = array_count_values($array);
$filtered = array_filter($array, create_function('$value',
    'global $counts; return $counts[$value] > 1;'));
var_dump($filtered);

演示:https://eval.in/68255

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