How to deduplicate an array using PHP

In PHP, array is a very important data type that can be used to store and operate large amounts of data. In actual development, we often need to read data from the database and store it in an array. However, since there may be duplicate data in the database, these duplicate data will also be stored in the array, causing the array to become bloated. Therefore, when using arrays to store database data, we need to deduplicate the arrays in order to better manage and operate the data. In this article, we will introduce how to deduplicate an array using PHP.

1. Use the array_unique() function in PHP

PHP provides an array deduplication function - array_unique(). This function removes duplicate values ​​from an array and returns a new array. Using this function is extremely simple, just pass the array that needs to be deduplicated as the parameter of the function.

For example, we have an array that stores numbers, which contains multiple identical numbers:

$numbers = array(1, 2, 3, 4, 5, 1, 2, 3);

We can use the array_unique() function to deduplicate the array. The code is as follows:

$unique_numbers = array_unique($numbers);

echo var_dump($ unique_numbers);

After executing this code, the output result is as follows:

array(5) {
[0]=>
int(1)
[1 ]=>
int(2)
[2]=>
int(3)
[3]=>
int(4)
[4]= >
int(5)
}

It can be seen that the duplicate values ​​​​in the original array have been successfully removed, and only one value is retained in the new array.

2. Using the in_array() function in PHP

In addition to using the array_unique() function, we can also use the in_array() function in PHP to deduplicate arrays . This function can determine whether a value already exists in the array, and if so, delete it. The implementation code is as follows:

function unique($array) {

$output = array();
foreach($array as $value) {
    if(!in_array($value, $output)) {
        $output[] = $value;
    }
}
return $output;

}

$numbers = array(1, 2, 3, 4, 5, 1, 2, 3);

$unique_numbers = unique($numbers);

echo var_dump($unique_numbers);

After executing this code, the output result is the same as the previous method , are all arrays after successful deduplication. The advantage of this method is that the deduplication method can be customized, for example, deduplication operations can be performed on different data types.

3. Use the array_flip() function in PHP

In addition to the first two methods, you can also use the array_flip() function in PHP to deduplicate the array. This function can flip the keys and values ​​in the array. If there are duplicate values, only one value will be retained. The code is implemented as follows:

$numbers = array(1, 2, 3, 4, 5, 1, 2, 3);

$unique_numbers = array_flip($numbers);

$unique_numbers = array_flip($unique_numbers);

echo var_dump($unique_numbers);

After executing this code, the output result is the same as the first two methods, both of which are successful deduplication the array after.

Summary

The above three methods can all deduplicate PHP arrays, and they are very convenient to use. In actual development, we can choose an appropriate method for deduplication according to the specific situation in order to better manage and operate data. Of course, when encountering some more complex arrays that require customized deduplication methods, we can also use other functions and algorithms in PHP to operate, which need to be selected and adjusted according to the specific situation.

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