从多个嵌套数组中获取所有组合

Question

我正在尝试在 PHP 中提出一种算法来获取嵌套数组的所有组合：

Array
(
    [0] => Array
        (
            [0] => Option Object
                (
                    [strValue] => rough
                )

            [1] => Option Object
                (
                    [strValue] => smooth
                )

            [2] => Option Object
                (
                    [strValue] => coarse
                )

        )

    [1] => Array
        (
            [0] => Option Object
                (
                    [strValue] => shiney
                )

            [1] => Option Object
                (
                    [strValue] => mat
                )

        )

    [2] => Array
        (
            [0] => Option Object
                (
                    [strValue] => Large
                )

            [1] => Option Object
                (
                    [strValue] => Medium
                )

            [2] => Option Object
                (
                    [strValue] => Small
                )

            [3] => Option Object
                (
                    [strValue] => very large
                )

        )

)

所以我会得到类似的东西：

-粗糙，闪亮，大

-粗糙，闪亮，小

-粗糙，闪亮，中等

-粗糙，闪亮，非常大

-光滑，闪亮，大

-光滑，闪亮，小

-光滑，闪亮，中等

-光滑，闪亮，非常大

等（在本例中应为 24）

我已经尝试了各种 foreach 示例和一些基本的递归函数，但我似乎没有得到什么快。如果有人能给出如何解决这个问题的基本大纲，我将非常感激，谢谢！

Answer 1

我刚刚写了这个，它适用于任何长度的数组..

<?php

function cartesian_product($a) {
  $result = array(array());
  foreach ($a as $list) {
    $_tmp = array();
    foreach ($result as $result_item) {
      foreach ($list as $list_item) {
        $_tmp[] = array_merge($result_item, array($list_item));
      }
    }
    $result = $_tmp;
  }
  return $result;
}


// Let's test this..                                                                                                                                                                                    

header('Content-type: text/plain');

$a = array(
  array('rough','smooth','coarse'),
  array('shiney','mat'),
  array('small','medium','large','x-large'),
);

$result = cartesian_product($a);
foreach ($result as $row) {
  print implode(", ", $row) ."\n";
}

编辑：稍微改进了代码..

Answer 2

是时候嵌套一些 foreach 循环了！

<?php
$array1 = array('rough', 'smooth', 'coarse');
$array2 = array('shiny', 'matte');
$array3 = array('very large', 'large', 'medium', 'small');

foreach($array1 as $i)
    foreach($array2 as $j)
        foreach($array3 as $k)
            $output[] = "$i, $j, $k";

var_dump($output);
/* ouput
array
  0 => string 'rough, shiny, very large' (length=24)
  1 => string 'rough, shiny, large' (length=19)
  2 => string 'rough, shiny, medium' (length=20)
  3 => string 'rough, shiny, small' (length=19)
  4 => string 'rough, matte, very large' (length=24)
  5 => string 'rough, matte, large' (length=19)
  6 => string 'rough, matte, medium' (length=20)
  7 => string 'rough, matte, small' (length=19)
  8 => string 'smooth, shiny, very large' (length=25)
  9 => string 'smooth, shiny, large' (length=20)
  10 => string 'smooth, shiny, medium' (length=21)
  11 => string 'smooth, shiny, small' (length=20)
  12 => string 'smooth, matte, very large' (length=25)
  13 => string 'smooth, matte, large' (length=20)
  14 => string 'smooth, matte, medium' (length=21)
  15 => string 'smooth, matte, small' (length=20)
  16 => string 'coarse, shiny, very large' (length=25)
  17 => string 'coarse, shiny, large' (length=20)
  18 => string 'coarse, shiny, medium' (length=21)
  19 => string 'coarse, shiny, small' (length=20)
  20 => string 'coarse, matte, very large' (length=25)
  21 => string 'coarse, matte, large' (length=20)
  22 => string 'coarse, matte, medium' (length=21)
  23 => string 'coarse, matte, small' (length=20)
*/
?>

Answer 3

这是psuedo-PHP中的蛮力（最差效率）算法：

$array1 = $array[0];
$array2 = $array[1];
$array3 = $array[2];

$results = array();
for( $i = 0; $i < count( $array1); $i++)
    for( $j = 0; $j < count( $array2); $j++)
        for( $k = 0; $k < count( $array3); $k++)
            $results[] = $array1[$i] . ',' . $array2[$j] . ',' . $array3[$k];