How to convert 2D array to 1D array using PHP

In PHP, a two-dimensional array is an array composed of multiple one-dimensional arrays, which is a very common data structure in programming. However, in some specific scenarios, we may need to convert a two-dimensional array into a one-dimensional array to facilitate program use and processing.

Below, I will introduce how to use PHP to convert a two-dimensional array into a one-dimensional array.

1. Use foreach loop

The most common method is to use foreach loop to extract each element of the two-dimensional array and store it in a new one-dimensional array.

$array = array(
    array('id' => 1, 'name' => 'Tom'),
    array('id' => 2, 'name' => 'Jerry')
);

$newArray = array();
foreach ($array as $value) {
    foreach ($value as $val) {
        $newArray[] = $val;
    }
}
print_r($newArray);

Output result:

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

2. Use array_reduce function

We can also use PHP's array_reduce function to process two-dimensional arrays.

$array = array(
    array('id' => 1, 'name' => 'Tom'),
    array('id' => 2, 'name' => 'Jerry')
);

$newArray = array_reduce($array, function ($result, $item) {
    return array_merge($result, array_values($item));
}, array());

print_r($newArray);

Output result:

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

3. Use array_column function

If we only need to extract a certain column in the two-dimensional array, we can use PHP's array_column function.

$array = array(
    array('id' => 1, 'name' => 'Tom', 'age' => 18),
    array('id' => 2, 'name' => 'Jerry', 'age' => 20)
);

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

Output result:

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

4. Use the function to recursively convert the array

If the nested dimensions of the two-dimensional array are not fixed, we can use the recursive function to convert.

$array = array(
    array('id' => 1, 'name' => 'Tom', 'languages' => array('PHP', 'Java')),
    array('id' => 2, 'name' => 'Jerry', 'languages' => array('Python', 'C++'))
);

function convert($array) {
    $newArray = array();
    foreach ($array as $value) {
        if (is_array($value)) {
            $newArray = array_merge($newArray, convert($value));
        } else {
            $newArray[] = $value;
        }
    }
    return $newArray;
}

$newArray = convert($array);
print_r($newArray);

Output result:

Array (
    [0] => 1
    [1] => Tom
    [2] => PHP
    [3] => Java
    [4] => 2
    [5] => Jerry
    [6] => Python
    [7] => C++
)

The above are several methods of converting two-dimensional arrays into one-dimensional arrays. Choosing the appropriate method according to the actual situation can greatly improve the efficiency and readability of the code. .

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