How to Efficiently Transpose Multidimensional Arrays in PHP?

Transpose Multidimensional Arrays in PHP

In the realm of PHP, working with multidimensional arrays often requires manipulation to achieve desired data representations. One such transformation is transposing the array, effectively flipping its rows and columns to create a new array with restructured dimensions.

How to Transpose a Multidimensional Array in PHP

The simplest approach to transpose a multidimensional array in PHP is to use a combination of array_unshift() and call_user_func_array(). Here's how you can do it:

function transpose($array) {
    array_unshift($array, null);
    return call_user_func_array('array_map', $array);
}

This function works by adding a null element to the beginning of the array, which acts as a placeholder for the array keys. Then, call_user_func_array() uses array_map to create a new array by mapping a function that simply returns the elements of the original array. The result is a transposed array.

A More Generalized Solution

For more complex scenarios involving arrays with multiple dimensions, a more generalized solution is required. The goal is to create a function that transposes an array regardless of its number of dimensions, such that the following equation holds true:

$foo[j][k][...][x][y][z] = $bar[z][k][...][x][y][j]

Here's an example of a recursive function that can achieve this:

function transposeRecursive($array) {
    if (!is_array($array)) {
        return $array;
    }
    return array_map(function($item) {
        return transposeRecursive($item);
    }, $array[0]) + transposeRecursive(array_slice($array, 1));
}

This function iteratively processes the array, transposing its dimensions recursively until it reaches the innermost array. By combining transposition with array slicing, it effectively restructures the array, ensuring that the equation mentioned earlier holds true.

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