How to convert a two-dimensional array into a one-dimensional array in php

When performing some array processing operations, sometimes it is necessary to convert multi-dimensional arrays into one-dimensional arrays. This article will introduce some methods to convert two-dimensional arrays into one-dimensional arrays in php.

Method 1: Loop traversal

A simple method is to use a foreach loop to traverse the two-dimensional array and add its elements to a one-dimensional array.

function array2To1($arr2){
    $arr1 = array();
    foreach($arr2 as $v){
        foreach($v as $v2){
            $arr1[] = $v2;
        }
    }
    return $arr1;
}

Usage example:

$arr2 = array(array(1,2),array(3,4),array(5,6));
$arr1 = array2To1($arr2);
print_r($arr1);
// Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 )

Method 2: Recursion

Another commonly used method is to use recursion to process multi-dimensional arrays and peel them layer by layer into one-dimensional arrays.

function array2To1($arr2){
    $arr1 = array();
    foreach($arr2 as $v){
        if(is_array($v)){
            $arr1 = array_merge($arr1,array2To1($v));
        }else{
            $arr1[] = $v;
        }
    }
    return $arr1;
}

Usage example:

$arr2 = array(array(1,2),3,array(array(4,5),6),7);
$arr1 = array2To1($arr2);
print_r($arr1);
// Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => 7 )

Method 3: Use PHP built-in functions

PHP provides some built-in functions to process multi-dimensional arrays, including array_reduce(), array_merge_recursive() and call_user_func_array() etc.

function array2To1($arr2){
    return call_user_func_array('array_merge_recursive', $arr2);
}

Usage example:

$arr2 = array(array(1,2),array(3,4),array(5,6));
$arr1 = array2To1($arr2);
print_r($arr1);
// Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 )

After actual testing, using method three is more time-consuming, so this method is not recommended when processing large arrays.

Summary:

Each method has its own advantages and disadvantages, and which method to choose ultimately depends on the specific needs and scenarios. I hope this article can be helpful to you. If you have a better method, please share it in the comment area.

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