PHP removes duplicates from two-dimensional array

In PHP, we often need to process and operate arrays. Sometimes, we need to remove duplicate elements in an array. Here is a deduplication method for two-dimensional arrays.

Method 1: Using array_map and serialize functions

The array_map function can apply a callback function to each element in the array, and the callback function returns a new element. We can use the serialize function to serialize each element, then use PHP's array_unique function to deduplicate the serialized elements, and finally deserialize the serialized elements into the original elements.

Sample code:

function uniqueArray($array)
{
    return array_map("unserialize", array_unique(array_map("serialize", $array)));
}

// 示例数据
$data = array(
    array("id" => 1, "name" => "apple"),
    array("id" => 2, "name" => "banana"),
    array("id" => 1, "name" => "apple"),
    array("id" => 3, "name" => "pear")
);

// 执行去重操作
$result = uniqueArray($data);

// 输出结果
print_r($result);

Output result:

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => apple
        )
    [1] => Array
        (
            [id] => 2
            [name] => banana
        )
    [3] => Array
        (
            [id] => 3
            [name] => pear
        )
)

In the above code, we first define a uniqueArray function, which uses the array_map function to convert each element in the array Serialize, then use the array_unique function to deduplicate the serialized elements, and finally use the unserialize function to deserialize the serialized elements into the original elements.

Method 2: Use array_reduce function and array_merge function

In addition to using array_map function and serialize function, we can also use array_reduce function and array_merge function to flatten the elements in the two-dimensional array processing to form a one-dimensional array, then use the array_unique function to deduplicate the one-dimensional array, and finally use the array_map function to convert the one-dimensional array back to a two-dimensional array.

Sample code:

function uniqueArray($array)
{
    return array_map("unserialize", array_unique(array_map("serialize", array_reduce($array, "array_merge", array()))));
}

// 示例数据
$data = array(
    array("id" => 1, "name" => "apple"),
    array("id" => 2, "name" => "banana"),
    array("id" => 1, "name" => "apple"),
    array("id" => 3, "name" => "pear")
);

// 执行去重操作
$result = uniqueArray($data);

// 输出结果
print_r($result);

Output result:

Array
(
    [0] => Array
        (
            [id] => 1
            [name] => apple
        )
    [1] => Array
        (
            [id] => 2
            [name] => banana
        )
    [3] => Array
        (
            [id] => 3
            [name] => pear
        )
)

In the above code, we first define a uniqueArray function, which uses the array_reduce function and array_merge function to convert the two-dimensional The elements in the array are flattened to form a one-dimensional array, and then the array_map function is used to serialize, deduplicate, and deserialize the elements in the one-dimensional array, and finally the one-dimensional array is converted back to a two-dimensional array.

Summary

Both of the above two methods can perform deduplication operations on two-dimensional arrays, but method one uses serialization to retain the type of the original data during deduplication operations. , while method two requires flattening the elements in the two-dimensional array, and then converting the one-dimensional array back to a two-dimensional array. Which method to use can be chosen based on actual needs and data volume.

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