How to remove duplicate values ​​from php two-dimensional array

In PHP, two-dimensional array is a very popular data structure. However, when we need to deduplicate data in a two-dimensional array, we may encounter some difficulties.

This article will introduce how to deduplicate two-dimensional arrays in PHP and retain unique values. We'll discuss two common practices: using a loop and using the array_map() function.

1. Using loops

Using a loop to traverse a two-dimensional array to find duplicate values ​​and delete them is the most direct method. Here is a sample code:

function unique_arr($array2D){
    foreach ($array2D as $k=>$v){
        $tem[$k] = serialize($v);
    }
    $tem = array_unique($tem); 
    foreach ($tem as $k=>$v){
        $array[$k] = unserialize($v);
    }
    return $array;
}

In the above code, we first use a foreach loop to traverse the two-dimensional array, serialize the array and store it in a temporary array $tem. Then we use the array_unique() function to remove duplicate values ​​in $tem. Finally, we use the foreach loop again to deserialize and store it in the array $array. Ultimately, the function returns a non-duplicating two-dimensional array.

2. Using the array_map() function

In PHP, the array_map() function can be used to execute a callback function on each element in the array. Removing duplicate values ​​from a two-dimensional array can also be easily done using the array_map() function. The code example is as follows:

function unique_arr($array2D){
    $serialize_array = array_map('serialize', $array2D);
    $unique_serialize_array = array_unique($serialize_array);
    $array = array_map('unserialize', $unique_serialize_array);
    return $array;
}

Like the first method, in this example code, we first serialize and store the array in a new array $serialize_array. Next, we use the array_unique() function to remove duplicate values ​​in $serialize_array. Finally, we use the array_map() function to deserialize the serialized array and store it in $array, ultimately returning a non-duplicate two-dimensional array.

3. Summary

In PHP, there are two common ways to remove duplicate values ​​from a two-dimensional array: using a loop and using the array_map() function. Although both methods can achieve functionality, using the array_map() function is easier to read and understand due to its simple and understandable nature.

In short, when processing two-dimensional arrays, we need to pay attention to various operations on the array in order to process our data more efficiently and conveniently.

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