How to convert one-dimensional array to three-dimensional array in php

For PHP programmers, arrays are a very important concept and an essential data type in daily work. In PHP, arrays can be divided into one-dimensional arrays, two-dimensional arrays, and multi-dimensional arrays. Among them, one-dimensional array is the most basic and common array type. In some special occasions, we need to convert a one-dimensional array into a three-dimensional array, so how to achieve this? This article will give you a detailed introduction to the relevant knowledge and implementation methods of converting one-dimensional arrays to three-dimensional arrays in PHP.

1. What is a one-dimensional array?

In PHP, a one-dimensional array is an array type with only one dimension, also called a linear array. Each element of it has only one data content and one corresponding keyword, and the two are connected with =>. The specific format is as follows:

array(key=>value, key=>value , …)

Among them, key represents the keyword corresponding to the element, and value represents the numerical value or data content corresponding to the element.

2. What is a three-dimensional array?

Three-dimensional array is also called multi-dimensional array, which refers to an array type containing three or more dimensions. A three-dimensional array is composed of multiple two-dimensional arrays, while a two-dimensional array is composed of multiple one-dimensional arrays. Each element of a three-dimensional array contains one or more such two-dimensional arrays, and each two-dimensional array contains one or more such one-dimensional arrays. Each element of the three-dimensional array has only one data content and one corresponding keyword. The two are also connected with =>, and its complete format is:

array(
key1 => array(

key2 => array(
  key3 => value,
  key3 => value,
  ...
),
key2 => array(
  key3 => value,
  key3 => value,
  ...
),
...

),
key1 => array(

key2 => array(
  key3 => value,
  key3 => value,
  ...
),
key2 => array(
  key3 => value,
  key3 => value,
  ...
),
...

),
...
)

where key1 represents the One-dimensional keywords, key2 represents the second-dimensional keyword, key3 represents the third-dimensional keyword, and value represents the data content corresponding to each element.

3. How to convert a one-dimensional array to a three-dimensional array in PHP?

In some special occasions, we need to convert a one-dimensional array into a three-dimensional array. In this case, we need to use some array functions in PHP to achieve this. Usually, we can use the following method to convert a one-dimensional array into a three-dimensional array:

$arr ​​= array(

array('name' => '张三', 'age' => 18, 'sex' => '男'),
array('name' => '李四', 'age' => 20, 'sex' => '女'),
array('name' => '王五', 'age' => 22, 'sex' => '女'),
array('name' => '赵六', 'age' => 24, 'sex' => '男')</p>
<p>);</p>
<p> $newArr = array();</p>
<p>foreach ($arr as $value) {</p>
<pre class="brush:php;toolbar:false">$newArr[$value['sex']][$value['age']][] = array('name' => $value['name']);

}

print_r($newArr);
?>

The execution result of the above code is as follows:

Array
(

[男] => Array
    (
        [18] => Array
            (
                [0] => Array
                    (
                        [name] => 张三
                    )

            )

        [24] => Array
            (
                [0] => Array
                    (
                        [name] => 赵六
                    )

            )

    )

[女] => Array
    (
        [20] => Array
            (
                [0] => Array
                    (
                        [name] => 李四
                    )

            )

        [22] => Array
            (
                [0] => Array
                    (
                        [name] => 王五
                    )

            )

    )

)

As mentioned above, we first need to define an empty three-dimensional array$ newArr to store the processed data, and then use foreach to traverse the one-dimensional array $arr. During the traversal process, we classify each element according to its gender and age, and gradually expand a new three-dimensional array, and finally store the processed data into $newArr.

It should be noted that the above example is only a specific implementation method. In fact, according to different actual needs, we can also use other methods to achieve conversion between one-dimensional arrays and three-dimensional arrays.

4. Summary

This article introduces in detail the relevant knowledge of one-dimensional arrays and three-dimensional arrays in PHP, and how to convert one-dimensional arrays to three-dimensional arrays. It should be noted that in actual work, we need to flexibly use various array functions and methods and choose the optimal implementation method according to specific needs to improve the readability and maintainability of the code.

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