Merge Two Arrays & Remove Duplicate Items in PHP
Given two arrays, the task is to merge both arrays and remove the duplicate elements from from merged array in PHP.
Below are the approaches to merge two arrays and remove duplicate items in PHP:
Table of Content
- Using array_merge() and array_unique() Function
- Using array_merge() with array_flip() Function
- Using array_merge() with array_values() and array_filter() Functions
Using array_merge() and array_unique() Function
The array_merge() function merges the elements of one or more arrays, while the array_unique() function removes duplicate values from an array.
Example: This example shows the use of the above-explained approach.
<?php
// Declare two arrays
$arr1 = [1, 2, 3, 4];
$arr2 = [3, 4, 5, 6];
// Merge the arrays
$mergedArr = array_merge($arr1, $arr2);
// Remove duplicates
$uniqueArr = array_unique($mergedArr);
print_r($uniqueArr);
?>
Output
Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
[6] => 5
[7] => 6
)
Explanation:
- array_merge($arr1, $arr2) function combines the elements of $arr1 and $arr2 into a single array.
- array_unique($mergedArr) function removes any duplicate values from the merged array.
Using array_merge() with array_flip() Function
Another method to ensure unique elements after merging is by combining array_merge() with array_flip() and array_keys(). This approach relies on the fact that keys in an associative array must be unique.
Example: This example shows the use of the above-explained approach.
<?php
// Declare two arrays
$arr1 = [1, 2, 3, 4];
$arr2 = [3, 4, 5, 6];
// Merge the arrays
$mergedArr = array_merge($arr1, $arr2);
// Flip the array to make values
// keys and then back
$uniqueArr = array_keys(array_flip($mergedArr));
print_r($uniqueArr);
?>
Output
Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
[4] => 5
[5] => 6
)
Explanation:
- array_merge($arr1, $arr2) function combines the elements of $arr1 and $arr2.
- array_flip($mergedArr) function flips the array, making values keys and thus ensuring uniqueness.
- array_keys(array_flip($mergedArr)) function retrieves the unique values from the flipped array.
Using array_merge() with array_values() and array_filter() Functions
This approach uses array_merge() to combine arrays, array_filter() to remove duplicates, and array_values() to reindex the array.
Example: This example shows the use of the above-explained approach.
<?php
// Declare two arrays
$arr1 = [1, 2, 3, 4];
$arr2 = [3, 4, 5, 6];
// Merge the arrays
$mergedArr = array_merge($arr1, $arr2);
// Remove duplicates and reindex the array
$uniqueArr = array_values(
array_filter(array_unique($mergedArr))
);
print_r($uniqueArr);
?>
Output
Array
(
[0] => 1
[1] => 2
[2] => 3
[3] => 4
[4] => 5
[5] => 6
)
Explanation:
- array_merge($arr1, $arr2) function combines the elements of $arr1 and $arr2.
- array_unique($mergedArr) function removes duplicate values.
- array_filter() function filters out any null or false values.
- array_values() function reindexes the array to have sequential keys.