如何从PHP多维数组中删除重复值?

示例数组:

Array
(
    [0] => Array
    (
        [0] => abc
        [1] => def
    )

    [1] => Array
    (
        [0] => ghi
        [1] => jkl
    )

    [2] => Array
    (
        [0] => mno
        [1] => pql
    )

    [3] => Array
    (
        [0] => abc
        [1] => def
    )

    [4] => Array
    (
        [0] => ghi
        [1] => jkl
    )

    [5] => Array
    (
        [0] => mno
        [1] => pql
    )

)

当前回答

对此,array_unique()文档上的用户注释提供了许多解决方案。这是其中之一:

kenrbnsn at rbnsn dot com 27-Sep-2005 12:09 Yet another Array_Unique for multi-demensioned arrays. I've only tested this on two-demensioned arrays, but it could probably be generalized for more, or made to use recursion. This function uses the serialize, array_unique, and unserialize functions to do the work. function multi_unique($array) { foreach ($array as $k=>$na) $new[$k] = serialize($na); $uniq = array_unique($new); foreach($uniq as $k=>$ser) $new1[$k] = unserialize($ser); return ($new1); }

这来自http://ca3.php.net/manual/en/function.array-unique.php#57202。

其他回答

如果"remove duplicate "的意思是"remove duplicate,但保留一个",一个解决方案可能是首先在"identifier column"上应用array_unique(…),然后在原始数组中删除所有已从列数组中删除的键:

$array = [
    [
        'id' => '123',
        'foo' => 'aaa',
        'bar' => 'bbb'
    ],
    [
        'id' => '123',
        'foo' => 'ccc',
        'bar' => 'ddd'
    ],
    [
        'id' => '567',
        'foo' => 'eee',
        'bar' => 'fff'
    ]
];

$ids = array_column($array, 'id');
$ids = array_unique($ids);
$array = array_filter($array, function ($key, $value) use ($ids) {
    return in_array($value, array_keys($ids));
}, ARRAY_FILTER_USE_BOTH);

结果是:

Array
(
    [0] => Array
        (
            [id] => 123
            [foo] => aaa
            [bar] => bbb
        )

    [2] => Array
        (
            [id] => 567
            [foo] => eee
            [bar] => fff
        )

)

对此,array_unique()文档上的用户注释提供了许多解决方案。这是其中之一:

kenrbnsn at rbnsn dot com 27-Sep-2005 12:09 Yet another Array_Unique for multi-demensioned arrays. I've only tested this on two-demensioned arrays, but it could probably be generalized for more, or made to use recursion. This function uses the serialize, array_unique, and unserialize functions to do the work. function multi_unique($array) { foreach ($array as $k=>$na) $new[$k] = serialize($na); $uniq = array_unique($new); foreach($uniq as $k=>$ser) $new1[$k] = unserialize($ser); return ($new1); }

这来自http://ca3.php.net/manual/en/function.array-unique.php#57202。

我对这个问题进行了大量的思考,并确定了最佳解决方案应该遵循两个规则。

为了可伸缩性,在适当的地方修改数组;不复制到新数组 对于性能,每个比较应该只进行一次

考虑到这一点,并考虑到PHP的所有特性,下面是我提出的解决方案。与其他一些答案不同,它能够根据您想要的任何键删除元素。输入数组应该是数字键。

$count_array = count($input);
for ($i = 0; $i < $count_array; $i++) {
    if (isset($input[$i])) {
        for ($j = $i+1; $j < $count_array; $j++) {
            if (isset($input[$j])) {
                //this is where you do your comparison for dupes
                if ($input[$i]['checksum'] == $input[$j]['checksum']) {
                    unset($input[$j]);
                }
            }
        }
    }
}

唯一的缺点是迭代完成时键不是按顺序排列的。如果你随后只使用foreach循环,这不是问题,但如果你需要使用for循环,你可以输入$input = array_values($input);上面之后要重新编号键。

从5.2.9开始,如果你像这样使用SORT_REGULAR标志,你可以使用array_unique():

array_unique($array, SORT_REGULAR);

这使得函数比较元素是否相等,就像使用了$a == $b一样,这非常适合您的情况。

输出

Array
(
    [0] => Array
        (
            [0] => abc
            [1] => def
        )

    [1] => Array
        (
            [0] => ghi
            [1] => jkl
        )

    [2] => Array
        (
            [0] => mno
            [1] => pql
        )

)

但是请记住,文档声明:

Array_unique()并不用于多维数组。

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => john
        )

    [1] => Array
        (
            [id] => 2
            [name] => smith
        )

    [2] => Array
        (
            [id] => 3
            [name] => john
        )

    [3] => Array
        (
            [id] => 4
            [name] => robert
        )

)

$temp = array_unique(array_column($array, 'name'));
$unique_arr = array_intersect_key($array, $temp);

这将从数组中删除重复的名称。按键唯一