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

PHP is a very popular programming language, especially in the world of web development. For PHP programmers, working with arrays is a very common task. In many cases, we need to convert a two-dimensional array into a one-dimensional array. This article explains how to achieve this in PHP.

What are two-dimensional arrays and one-dimensional arrays?

In PHP, an array can be thought of as a variable type used to store multiple values. Each of these values ​​is called an element, and each element is identified by a unique index. There are two array types in PHP: one-dimensional arrays and two-dimensional arrays.

A one-dimensional array is a simple list consisting of an index and a value, where each value has a unique index. We can use iterators to traverse a one-dimensional array.

A two-dimensional array is a list composed of multiple lists. They consist of a main index and a sub-index. We need to use nested iterators to traverse a two-dimensional array.

How to convert a two-dimensional array into a one-dimensional array?

In PHP, we can easily use the built-in array_column function to convert a two-dimensional array into a one-dimensional array. The array_column function allows us to take a column from a multidimensional array and return a new one-dimensional array.

The syntax of array_column is as follows:

array_column(array $array, mixed $column_key, mixed $index_key = null): array

Among them, the $array parameter is the specified array, $column_key is the key name or position of the value to be returned, and $index_key is used as the new array key. Key name or location. If the $index_key parameter is not provided, a numeric index is used.

The following is an example of converting a two-dimensional array into a one-dimensional array:

$array = array(
    array('id' => 1, 'name' => 'Tom', 'age' => 30),
    array('id' => 2, 'name' => 'Jerry', 'age' => 25),
    array('id' => 3, 'name' => 'Mike', 'age' => 35)
);

$names = array_column($array, 'name');
print_r($names);

This will output the following results:

Array
(
    [0] => Tom
    [1] => Jerry
    [2] => Mike
)

In this example, we use the array_column function to convert The 'name' value of each element in the two-dimensional array $array is extracted to generate a new one-dimensional array $names.

It should be noted that if you want to use a numeric index as the new array key, use a number in the $index_key parameter, as follows:

$ids = array_column($array, 'id', 0);
print_r($ids);

This will output the following results:

Array
(
    [0] => 1
    [1] => 2
    [2] => 3
)

In this example, we set the key of the new array to the first element of the original 2D array.

Conclusion

Manipulating arrays is a very common task in PHP development. Converting a two-dimensional array to a one-dimensional array is one operation in this task. In PHP, we can easily achieve this using the array_column function. This function allows us to extract a column from a two-dimensional array and generate a new one-dimensional array.

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