How to remove identical arrays in php

In PHP, it is often necessary to operate on arrays. One of the common operations is to remove the same data. This situation is very common during data processing, filtering or deduplication. So, in specific operations, how do we use PHP to remove identical arrays?

1. Use the array_unique() function to remove identical elements

PHP’s built-in function array_unique() can be used to remove duplicate elements in an array. This function returns a new array containing only the distinct elements that appeared in the original array. Below, we demonstrate how to use this function:

<?php
$colors = array("red","green","blue","red","yellow","blue");
$unique_colors = array_unique($colors);
print_r($unique_colors);
?>

In this code, we define an array $colors, some of which are repeated. Through the processing of array_unique() function, the new array $unique_colors after removing duplicate elements is returned. We can see that the output result is as follows:

Array
(
[0] => red
[1] => green
[2] => blue
[4] => yellow
)

As you can see from the output, the duplicate elements in the $colors array have been removed from the $unique_colors array.

2. Use a custom function to remove identical elements

Sometimes, we need to use a custom function to remove duplicate elements in an array. This method is more troublesome to implement, and you need to write your own code to process the array.

<?php
function custom_unique($array){
    $result = array();
    foreach($array as $value){
        if(!in_array($value,$result)){
            $result[] = $value;
        }
    }
    return $result;
}
$colors = array("red","green","blue","red","yellow","blue");
$unique_colors = custom_unique($colors);
print_r($unique_colors);
?>

In this code, we define a custom function custom_unique() to remove duplicate elements in the $colors array. The implementation process of this function is: traverse the initial array, use the in_array() function to determine whether the element has appeared in the new array $unique_colors, if not, add it to the new array $unique_colors, and finally return the processed new array. Running the above code will output results similar to the first method:

Array
(
[0] => red
[1] => green
[2] => blue
[4] => yellow
)

3. Use the array_diff() function to remove identical elements

The array_diff() function can be used to compare two arrays. Return the distinct elements between them. If our goal is to remove identical elements from an array, we can also use this feature to achieve it.

<?php
$colors = array("red","green","blue","red","yellow","blue");
$unique_colors = array_diff($colors,array_unique($colors));
print_r($unique_colors);
?>

In this code, we use the array_diff() function and array_unique() function to remove identical elements. First, we use the array_unique() function to get the array after removing duplicate elements, and then use the array_diff() function to compare the initial array and the array after deduplication, and return the different elements between the two arrays, which is what we need array.

Through the above three methods, we can more easily remove the same elements in the array. Which method to use depends on our actual needs and programming habits.

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