PHP encapsulated array deduplication method

In PHP, deduplication of arrays is one of the very basic tasks. However, in some cases, we need to encapsulate arrays to facilitate our code reuse and maintenance. This article will introduce how to use class methods to encapsulate array deduplication methods.

First, we need to create a class called ArrayUtils and add a static method called uniqueValues. This method will accept an array as a parameter and return a deduplicated array. The following is the basic structure of this class:

class ArrayUtils {
    public static function uniqueValues($array) {
        // code here
    }
}

Next, we need to write the deduplication logic. PHP provides many methods to deduplicate an array, such as using the array_unique() function, using loops and conditional statements, etc. Here, we will use array_flip() and array_keys() functions to implement deduplication. Specifically, we will use the array_flip() function to store the values ​​in an array as keys into another array, and then use the array_keys() function to extract those keys as the contents of the deduplicated array. Following is the code of uniqueValues() method:

public static function uniqueValues($array) {
    // use array_flip() and array_keys() to remove duplicate values
    return array_keys(array_flip($array));
}

Here, we use array_flip() function to convert the values ​​in the array into keys and use it to create a new array. Since array keys must be unique, all duplicate values ​​are combined into a single key in the new array. We then use the array_keys() function to extract these keys as the contents of the deduplicated array.

Now, we can use the uniqueValues() method of the ArrayUtils class to deduplicate any array. The following is an example:

// sample input array
$fruits = array('apple', 'banana', 'orange', 'apple', 'kiwi', 'kiwi');

// remove duplicates using ArrayUtils
$uniqueFruits = ArrayUtils::uniqueValues($fruits);

// output unique fruits
print_r($uniqueFruits);

Output result:

Array
(
    [0] => apple
    [1] => banana
    [2] => orange
    [3] => kiwi
)

As you can see, the duplicate entries have been removed and only one entry is included.

Finally, let's consider some possible improvements to enhance the readability and maintainability of our code. For example, we can add some parameters in the uniqueValues() method to control the details of the deduplication operation. For example:

public static function uniqueValues($array, $caseInsensitive = false, $preservingKeys = false) {
    // set flags for case-insensitive and preserving keys
    $flip = $caseInsensitive ? array_change_key_case($array, CASE_LOWER) : $array;
    $preserve = $preservingKeys ? 0 : ARRAY_FILTER_USE_KEY;
    
    // use array_flip() and array_keys() to remove duplicate values
    return array_keys(array_filter(array_flip($flip), $preserve));
}

Here, we added two parameters: $caseInsensitive and $preservingKeys. If $caseInsensitive is true, deduplication operations in arrays are case-insensitive. If $preservingKeys is true, the returned array will preserve the keys of the original input array.

We use the array_change_key_case() function to convert the case of array keys to lowercase to achieve case-insensitive deduplication. We also pass the $preservingKeys parameter to the array_filter() function to filter out elements that do not need to be preserved.

In summary, using class methods to encapsulate array deduplication methods can improve code reusability and maintainability. By adding parameters and detail handling, we can make the code more flexible and sophisticated.

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