PHP - 如何翻转二维数组的行和列

PHP - how to flip the rows and columns of a 2D array

提问by Gnuffo1

Normally I'd be asking how to turn something like this:

通常我会问如何转动这样的东西：

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

Into this:

进入这个：

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

But actually I want to turn it into this:

但实际上我想把它变成这样：

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

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.

换句话说，我想翻转行和列，但保持新数组的“宽度”和“高度”相同。我已经坚持了一个多小时。

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

这是我用来进行正常“翻转”的函数（第一个示例）：

function flip($arr)
{
    $out = array();

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

    return $out;
}

回答by Mark Elliot

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.

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步行过程中创建一个全新的阵列。

A solution will be of the form:

解决方案将采用以下形式：

$rows = count($arr);
$cols = count($arr[0]); // assumes non empty matrix
$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;
        }
    }
}

回答by chetan singhal

function flip_row_col_array($array) {
    $out = array();
    foreach ($array as  $rowkey => $row) {
        foreach($row as $colkey => $col){
            $out[$colkey][$rowkey]=$col;
        }
    }
    return $out;
}

回答by Nikolay

I had to write this one to inverse an array of name indexed arrays. It's very useful for printing php array as as html table, as it even fills missing elements with nulls so the number of is same for all rows of html table.

我不得不写这个来反转名称索引数组的数组。它对于将 php 数组打印为 html 表非常有用，因为它甚至用空值填充缺失的元素，因此 html 表的所有行的数量都相同。

  /**
  * Inverses a two dimentional array.
  * The second dimention can be <b>name indexed</b> arrays, that would be preserved.
  * This function is very useful, for example, to print out an html table
  * from a php array.
  * It returns a proper matrix with missing valus filled with null.
  *
  * @param type $arr input 2d array where second dimention can be. <b>name indexed</b>
  * arrays.
  * @return 2d_array returns a proper inverted matrix with missing values filled with
  * nulls
  * @author Nikolay Kitsul
  */
 public static function array_2D_inverse($arr) {
     $out = array();
     $ridx = 0;
     foreach ($arr as $row) {
         foreach ($row as $colidx => $val) {
             while ($ridx > count($out[$colidx]))
                 $out[$colidx][] = null;
             $out[$colidx][] = $val;
         }
         $ridx++;
     }
     $max_width = 0; 
     foreach($out as $v)
          $max_width = ($max_width < count($v)) ? count($v) : $max_width;
     foreach($out as $k => $v){
         while(count($out[$k]) < $max_width)
             $out[$k][] = null;
     }
     return $out;
 }

回答by Oritm

What you need is:

你需要的是：

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

回答by rckd

Got this simple one:

得到了这个简单的：

$matrix = [
  [1, 2, 3],
  [1, 2, 3],
  [1, 2, 3],
];

$flipped = array_map(function($col, $i) use($matrix){
  return array_map(function($row) use($matrix, $i){
    return $row[$i];
  }, $matrix);
}, $matrix, array_keys($matrix));

回答by James Dunsterville

$output_array = [];
foreach ($input_array as $column_id => $rows) {
    foreach ($rows as $row_id => $value) {
        if (!array_key_exists($row_id, $output_array)) {
            $output_array[$row_id] = [];
        }
        $output_array[$row_id][$column_id] = $value;
    }
}

is my usual solution, this just ensures that row id exists as a valid index before writing to it. This will preserve all keys, and switch rows and columns from $input_array into $output_array

是我通常的解决方案，这只是确保行 id 在写入之前作为有效索引存在。这将保留所有键，并将行和列从 $input_array 切换到 $output_array

回答by Bing

Modified version of the "accepted" answer, which works MUCH better IMHO:

“已接受”答案的修改版本，恕我直言，效果更好：

function array2DFlip($arr) {
 if(!is_array($arr) || count($arr) < 1 || !isset($arr[0])) return array();

 $out = array();

 foreach($arr as $row_id => $row){
    foreach($row as $col_id => $val){
        $out[$col_id][$row_id] = $val;
    }
 }

 return $out;
}

回答by user244724

here you go. It works. :)

干得好。有用。:)

$input1 = array(1,2,3);
$input2 = array(4,5,6);
$input3 = array(7,8,9);
$input4 = array(10,11,12);

$input = array($input1,$input2,$input3,$input4);

echo "\n input array";print_r($input);

// flipping matrices
$output = array();
$intern = array();

for($row=0; $row lt 4; $row++)
    for($col=0;$col lt 3;$col++)
        $intern[] = $input[$row][$col];

echo "\n intern ";print_r($intern);

// nesting the array
$count = 0;
$subcount = 0;

foreach($intern as $value)
{

    $output[$count][$subcount] = $value;
    $count++;

    if($subcount == 3)
    {
        break;
    }

    if($count == 4)
    {
        $count = 0;
        $subcount++;
    }


}


echo "\n final output ";print_r($output);

回答by Federico J. álvarez Valero

I have developed this code, based partially in a solution found here to flatten multidimensional arrays.

我开发了此代码，部分基于此处找到的用于展平多维数组的解决方案。

Hope it helps!

希望能帮助到你！

/**
 *
 * http://stackoverflow.com/questions/2289475/converting-php-array-of-arrays-into-single-array
 * @param array $array
 * @return array
 */
function arrayFlatten(array $array)
{
    $flatten = array();
    array_walk_recursive($array, function($value) use(&$flatten)
    {
        $flatten[] = $value;
    });

    return $flatten;
}

/**
 *
 *  Reorders an array to put the results ordered as a "N", instead of a "Z"  
 *
 * @static
 * @param $array Array to be ordered
 * @param $columns Number of columns of the "N"
 * @return void
 */
function ZOrderToNOrder($array, $columns)
{
    $maxRows = ceil(count($array) / $columns);
    $newArray = array();
    $colCounter = 0;
    $rowCounter = 0;
    foreach ($array as $element)
    {
        $newArray[$rowCounter][] = $element;
        $rowCounter++;
        if ($rowCounter == $maxRows)
        {
            $colCounter++;
            $rowCounter = 0;
        }
    }

    return arrayFlatten($newArray);
}

回答by aanton

falvarez, the ZOrderToNOrder function does not work correctly when one or more columns have got one more element that other columns (other > 1).

falvarez，当一列或多列比其他列多出一个元素（other > 1）时，ZOrderToNOrder 函数无法正常工作。

i think this code fix it:

我认为这段代码修复了它：

public static function ZOrderToNOrder($array, $columns) {
    $numElements = count($array);

    $maxRows = array();
    for ($i = 0; $i < $columns; $i++) {
        $maxRows[$i] = intval(ceil(($numElements - $i) / $columns));
    }

    $newArray = array();

    $rowCounter = 0;
    $colCounter = 0;
    foreach ($array as $element) {
        $newArray[$rowCounter][$colCounter] = $element;
        $rowCounter++;
        if ($rowCounter === $maxRows[$colCounter]) {
            $rowCounter = 0;
            $colCounter++;
        }
    }

    return self::arrayFlatten($newArray);
}

Regards,

问候，

Armando

阿曼多