Let’s talk about the conversion method of two-dimensional array in php

In PHP, array is a very common data structure and an important tool for processing data. In practical applications, we often need to convert a two-dimensional array into another form of array. This process requires some skills and methods. This article will introduce you to how to achieve two-dimensional array conversion.

1. Definition of two-dimensional array

First of all, we need to understand what a two-dimensional array is. In PHP, a two-dimensional array is composed of multiple one-dimensional arrays. Each one-dimensional array represents a row of data in a two-dimensional array.

For example, the following two-dimensional array contains three one-dimensional arrays, representing three rows of data respectively:

$arr = array(
  array(1,2,3),
  array(4,5,6),
  array(7,8,9)
);

2. Convert two-dimensional arrays into one-dimensional arrays

Sometimes, we need to convert a two-dimensional array into a one-dimensional array. At this time, you can use the array_reduce() function in PHP.

The array_reduce() function can receive an array and iterate over it. We can use this function to merge multiple one-dimensional arrays into a single one-dimensional array. The specific operation is as follows:

//将二维数组转化为一维数组
$new_arr = array_reduce($arr, 'array_merge', array());
print_r($new_arr);

This code first defines a new empty array $new_arr, and then uses the array_reduce() function to merge all one-dimensional arrays in the original two-dimensional array $arr into $new_arr. , and return.

In the above example, the value of $new_arr is:

Array ( [0] => 1 [1] => 2 [2] => 3 [3] => 4 [4] => 5 [5] => 6 [6] => 7 [7] => 8 [8] => 9 )

3. Merge two-dimensional arrays by rows

There is also a common The situation is that multiple two-dimensional arrays need to be merged into one two-dimensional array row by row. This operation is also relatively simple and can be completed using the array_merge() function in PHP.

The following is an example:

$arr1 = array(
  array(1,2,3),
  array(4,5,6)
);
 
$arr2 = array(
  array(7,8,9),
  array(10,11,12)
);
 
//按行合并两个二维数组
$new_arr = array_merge($arr1, $arr2);
print_r($new_arr);

In the above example, the value of $new_arr is:

Array
(
    [0] => Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
        )
 
    [1] => Array
        (
            [0] => 4
            [1] => 5
            [2] => 6
        )
 
    [2] => Array
        (
            [0] => 7
            [1] => 8
            [2] => 9
        )
 
    [3] => Array
        (
            [0] => 10
            [1] => 11
            [2] => 12
        )
)

4. Convert the two-dimensional array to json format

In JavaScript, JSON is a common data format. In PHP, we can easily use the json_encode() function to convert a two-dimensional array into a JSON format string. The following is an example:

$arr = array(
  array('id'=>1, 'name'=>'Tom', 'age'=>25),
  array('id'=>2, 'name'=>'Jack', 'age'=>30),
  array('id'=>3, 'name'=>'Mike', 'age'=>35)
);
 
//将二维数组转化为json格式
$json_str = json_encode($arr);
echo $json_str;

In the above example, the value of $json_str is:

[
    {"id":1,"name":"Tom","age":25},
    {"id":2,"name":"Jack","age":30},
    {"id":3,"name":"Mike","age":35}
]

5. Summary

Introduction to this article Several methods of converting two-dimensional arrays in PHP are described, including converting two-dimensional arrays into one-dimensional arrays, merging two-dimensional arrays by rows, and converting two-dimensional arrays into JSON format. I hope these methods can help you better use PHP to process data.

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