How to maintain key-value correspondence after deduplication in PHP array?

PHP Methods to maintain key-value correspondence after deduplication in an array include: using the array_unique() function to remove duplicate values, and then using the array_flip() function to exchange key-value pairs. Merge the original array with the deduplicated array, and use the array merging method to retain key-value correspondence.

PHP array maintains key value correspondence after deduplication

Introduction

In When dealing with PHP arrays, sometimes we need to remove duplicate elements while maintaining their key-value correspondence. This tutorial will show you how to use the array_unique() function in combination with other methods to achieve this goal.

array_unique() function

array_unique() function can be used to remove duplicate values ​​from an array. By default, it compares the values ​​in the array and retains the key-value correspondence of the first occurrence.

Code example

$array = ['foo', 'bar', 'baz', 'foo', 'xyz'];

$uniqueArray = array_unique($array);

print_r($uniqueArray);

Output:

Array
(
    [0] => foo
    [1] => bar
    [2] => baz
    [4] => xyz
)

Keep key value corresponding

In order to keep the array For key-value mapping of elements, we need to use additional steps. One way is to use the array_flip() function, which swaps the key and value of a key-value pair.

Code example

$flippedArray = array_flip($uniqueArray);

print_r($flippedArray);

Output:

Array
(
    [foo] => 0
    [bar] => 1
    [baz] => 2
    [xyz] => 4
)

Now, we have a unique array that keeps key-value correspondence.

Using merge

Another way to keep key-value correspondence is to use array merge. This method creates a new associative array using the original array and the deduplicated array.

Code Example

$newArray = array_merge($array, $uniqueArray);

print_r($newArray);

Output:

Array
(
    [0] => foo
    [3] => foo
    [1] => bar
    [4] => baz
    [2] => xyz
)

This method does not filter duplicate values, but it retains the key-value correspondence of the original array.

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