在不改变列数的情况下翻转(转置)二维数组的行和列 [英] Flip (transpose) the rows and columns of a 2D array without changing the number of columns

问题描述

通常，我会问如何像这样转换一个 4 行、3 列的数组:

Normally, I'd be asking how to turn a 4-rowed, 3-columned array like this:

1      2        3
4      5        6
7      8        9
10    11       12

变成一个 3 行、4 列的数组，例如:(我不想要这个)

Into a 3-rowed, 4-columned array like: (I DON'T WANT THIS)

1   4   7   10
2   5   8   11
3   6   9   12

但实际上，我想把它变成这样:(我想要这个)

But actually, I want to turn it into this: (I WANT THIS)

1   5   9
2   6   10
3   7   11
4   8   12

换句话说，我想翻转行和列，但保持相同的宽度"和高度"的新阵列.我已经坚持了一个多小时.

In other words, I want to flip the rows and columns, but keep the same "width" and "height" of the new array. I've been stuck on this for over an hour.

这是我用来进行正常翻转"的函数(第一个例子):

This is the function I'm using to do a normal "flip" (the first example):

function flip($arr)
{
    $out = array();
    foreach ($arr as $key => $subarr)
    {
        foreach ($subarr as $subkey => $subvalue)
        {
            $out[$subkey][$key] = $subvalue;
        }
    }
    return $out;
}

推荐答案

只需按照正确的顺序遍历数组即可.假设您有相对较小的阵列，最简单的解决方案就是在该过程中创建一个全新的阵列.

Just walk the array in the correct order. Assuming you have relatively small arrays, the easiest solution is just to create a brand new array during that walk.

解决方案将采用以下形式:

A solution will be of the form:

$rows = count($arr);
$ridx = 0;
$cidx = 0;

$out = array();

foreach($arr as $rowidx => $row){
    foreach($row as $colidx => $val){
        $out[$ridx][$cidx] = $val;
        $ridx++;
        if($ridx >= $rows){
            $cidx++;
            $ridx = 0;
        }
    }
}

这篇关于在不改变列数的情况下翻转(转置)二维数组的行和列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！