How to use PHP to implement the inversion operation of a two-dimensional array

In PHP programming, a two-dimensional array is a data structure used to store multiple data values. This kind of array can be used to store complex data structures such as table data and schedules. In some cases, it is necessary to invert a two-dimensional array, that is, to exchange rows and columns. For example, when displaying tabular data, it is often necessary to invert the columns and rows to better present the data. This article will introduce how to use PHP to implement the inversion operation of a two-dimensional array.

1. What is a two-dimensional array

In PHP, a two-dimensional array is an array that can contain multiple arrays. Each array contains a set of data values, and indexes are used to access these values. Here is an example of a simple 2D array:

$data = array(
    array("apple", "banana", "orange"),
    array("red", "yellow", "orange"),
    array("sweet", "sour", "sweet")
);

The above array contains 3 arrays, each containing 3 string values. To access these values, you can use the following code:

echo $data[0][0]; //输出 "apple"
echo $data[1][2]; //输出 "orange"
echo $data[2][1]; //输出 "sour"

2. Two-dimensional array inversion operation

In PHP, you can use the for loop statement and the foreach loop statement to traverse the two-dimensional array. value to implement the inversion operation of a two-dimensional array. The following is an example of using a for loop statement to implement a two-dimensional array inversion operation:

function array_invert($arr) {
    // 获取数组的行数和列数
    $rows = count($arr);
    $cols = count($arr[0]);
    // 创建倒置后的数组
    $invertArr = array();
    // 循环遍历数组的行与列
    for ($i = 0; $i < $cols; $i++) {
        for ($j = 0; $j < $rows; $j++) {
            $invertArr[$i][$j] = $arr[$j][$i];
        }
    }
    // 返回倒置后的数组
    return $invertArr;
}

In the above code, first obtain the number of rows and columns of the two-dimensional array, and then create an inverted array $invertArr. Then, the rows and columns of the two-dimensional array are traversed through two for loops. During the traversal process, the values ​​are copied into the inverted array, and finally the inverted array is returned.

The following is an example of using a function to invert a two-dimensional array:

$data = array(
    array("apple", "banana", "orange"),
    array("red", "yellow", "orange"),
    array("sweet", "sour", "sweet")
);

$invertData = array_invert($data);

// 输出倒置后的数组
foreach ($invertData as $row) {
    foreach ($row as $value) {
        echo $value . " ";
    }
    echo "<br/>";
}

In the above code, the two-dimensional array $data is first passed to the function, and the function returns the inverted array $invertData. Then, use a foreach loop to traverse the inverted array and output the values ​​to the page.

3. Summary

This article introduces the concept of two-dimensional arrays in PHP and the implementation method of inversion operation. By traversing the rows and columns of the two-dimensional array, the rows and columns of the two-dimensional array can be inverted. The inversion operation is useful in many situations, such as when displaying tabular data or calculating matrix products, where you need to invert a two-dimensional array.

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