多维数组中的数组排列保持键PHP

Posted 2023-03-31

【中文标题】多维数组中的数组排列保持键PHP

【英文标题】：Array permutations in multidimensional array keeping the keys PHP

【发布时间】：2011-08-23 11:31:42

【问题描述】：

这两天我一直在疯狂地试图完成这个，也许你能启发我。这是一个马投注排列。每次用户播放时，我都会得到一个多维数组（2 个级别）。第一级包含比赛 ID，第二级包含用户为该比赛选择的马。它看起来像这样：

$play = array
(
    '4' => array(7, 32),
    '8' => array(4),
    '2' => array(9),
    '12' => array('5'),
    '83' => array('10', '11', '12', ''),
    '9' => array('3'),
);

我需要知道这出戏的所有可能组合是什么。使用此功能可以轻松完成：

function permutations(array $array)

    switch (count($array)) 
        case 1:
            return $array[0];
            break;
        case 0:
            throw new InvalidArgumentException('Requires at least one array');
            break;
    

    $a = array_shift($array);
    $b = permutations($array);

    $return = array();
    foreach ($a as $key => $v) 
        if(is_numeric($v))
        
            foreach ($b as $key2 => $v2) 
                $return[] = array_merge(array($v), (array) $v2);
            
        
    

    return $return;

这会完美地返回一个包含所有可能组合的数组。到目前为止一切顺利，结果如下所示：

Array
(
    [0] => Array
        (
            [0] => 7
            [1] => 4
            [2] => 9
            [3] => 5
            [4] => 10
            [5] => 3
        )

    [1] => Array
        (
            [0] => 7
            [1] => 4
            [2] => 9
            [3] => 5
            [4] => 11
            [5] => 3
        )

    [2] => Array
        (
            [0] => 7
            [1] => 4
            [2] => 9
            [3] => 5
            [4] => 12
            [5] => 3
        )

    [3] => Array
        (
            [0] => 32
            [1] => 4
            [2] => 9
            [3] => 5
            [4] => 10
            [5] => 3
        )

    [4] => Array
        (
            [0] => 32
            [1] => 4
            [2] => 9
            [3] => 5
            [4] => 11
            [5] => 3
        )

    [5] => Array
        (
            [0] => 32
            [1] => 4
            [2] => 9
            [3] => 5
            [4] => 12
            [5] => 3
        )

)

我的问题：我需要将每匹马的数组“键”作为“种族 ID”，而不是 0、1、2、3。 我需要这样的结果：

Array
(
    [0] => Array
        (
            [4] => 7
            [8] => 4
            [2] => 9
            [12] => 5
            [83] => 10
            [9] => 3
        )

    [1] => Array
        (
            [4] => 7
            [8] => 4
            [2] => 9
            [12] => 5
            [83] => 11
            [9] => 3
        )

    [2] => Array
        (
            [4] => 7
            [8] => 4
            [2] => 9
            [12] => 5
            [83] => 12
            [9] => 3
        )

    [3] => Array
        (
            [4] => 32
            [8] => 4
            [2] => 9
            [12] => 5
            [83] => 10
            [9] => 3
        )

    [4] => Array
        (
            [4] => 32
            [8] => 4
            [2] => 9
            [12] => 5
            [83] => 11
            [9] => 3
        )

    [5] => Array
        (
            [4] => 32
            [8] => 4
            [2] => 9
            [12] => 5
            [83] => 12
            [9] => 3
        )

)

我怎样才能做到这一点？我知道这是一个很长的帖子，但我需要绘制这个。我在围绕函数递归时遇到问题，并且在每个循环中都完全迷失了。

【问题讨论】：

为什么在你的初始数组中有些值是数字，有些是字符串？为什么是空的？

因为它来自一个 html 复选框数组，所以用户可能会留下一些复选框为空。 permutations() 函数忽略不是整数的值。这不是问题:)

如何使用密钥请粘贴一些您希望制作的有效数组示例。

最后一个代码块包含需要的数组结构。谢谢！

【参考方案1】：

我也遇到了同样的问题，而 Danny 的解决方案对我不利。 我管理数千个排列并将它们存储在内存中非常昂贵。

这是我的解决方案：

/**
 * Calculate permutation of multidimensional array. Without recursion!
 * Ex.
 * $array = array(
 *   key => array(value, value),
 *   key => array(value, value, value),
 *   key => array(value, value),
 * );
 *
 * @copyright Copyright (c) 2011, Matteo Baggio
 * @param array $anArray Multidimensional array
 * @param function $isValidCallback User function called to verify the permutation. function($permutationIndex, $permutationArray)
 * @return mixed Return valid permutation count in save memory configuration, otherwise it return an Array of all permutations
 */
function permutationOfMultidimensionalArray(array $anArray, $isValidCallback = false) 

    // Quick exit
    if (empty($anArray))
        return 0;

    // Amount of possible permutations: count(a[0]) * count(a[1]) * ... * count(a[N])
    $permutationCount = 1;
    // Store informations about every column of matrix: count and cumulativeCount
    $matrixInfo = array();
    $cumulativeCount = 1;

    foreach($anArray as $aColumn) 

        $columnCount       = count($aColumn);
        $permutationCount *= $columnCount;

        // this save a lot of time!
        $matrixInfo[] = array(
            'count'           => $columnCount,
            'cumulativeCount' => $cumulativeCount
        );

        $cumulativeCount  *= $columnCount;
    

    // Save the array keys
    $arrayKeys = array_keys($anArray);
    // It needs numeric index to work
    $matrix = array_values($anArray);
    // Number of column
    $columnCount = count($matrix);
    // Number of valid permutation
    $validPermutationCount = 0;
    // Contain all permutations
    $permutations = array();

    // Iterate through all permutation numbers
    for ($currentPermutation = 0; $currentPermutation < $permutationCount; $currentPermutation++) 

        for ($currentColumnIndex = 0; $currentColumnIndex < $columnCount; $currentColumnIndex++) 
            // Here the magic!
            // I = int(P / (Count(c[K-1]) * ... * Count(c[0]))) % Count(c[K])
            // where:
            // I: the current column index
            // P: the current permutation number
            // c[]: array of the current column
            // K: number of the current column
            $index = intval($currentPermutation / $matrixInfo[$currentColumnIndex]['cumulativeCount']) % $matrixInfo[$currentColumnIndex]['count'];

            // Save column into current permutation
            $permutations[$currentPermutation][$currentColumnIndex] = $matrix[$currentColumnIndex][$index];
        

        // Restore array keys
        $permutations[$currentPermutation] = array_combine($arrayKeys, $permutations[$currentPermutation]);

        // Callback validate
        if ($isValidCallback !== false) 
            if ($isValidCallback($currentPermutation, $permutations[$currentPermutation]))
                $validPermutationCount++;
            // *** Uncomment this lines if you want that this function return all
            //     permutations
            //else
            //  unset($permutations[$currentPermutation]);
        
        else 
            $validPermutationCount++;
        

        // Save memory!!
        // Use $isValidCallback to check permutation, store into DB, etc..
        // *** Comment this line if you want that function return all
        //     permutation. Memory warning!!
        unset($permutations[$currentPermutation]);
    


    if (!empty($permutations))
        return $permutations;
    else
        return $validPermutationCount;



//
// How to?
//

$play = array(
    '4'  => array(7, 32),
    '8'  => array(4),
    '2'  => array(9),
    '12' => array('5'),
    '83' => array('10', '11', '12', ''), // <-- It accept all values, nested array too
    '9'  => array('3'),
);


$start = microtime(true);

// Anonymous function work with php 5.3.0
$validPermutationsCount = permutationOfMultidimensionalArray($play, function($permutationIndex, $permutationArray)

        // Here you can validate the permutation, print it, etc...
        // Using callback you can save memory and improve performance.
        // You don't need to cicle over all permutation after generation.
        printf('<p><strong>%d</strong>: %s</p>', $permutationIndex, implode(', ', $permutationArray));

        return true; // in this case always true
    );

$stop = microtime(true) - $start;

printf('<hr /><p><strong>Performance for %d permutations</strong><br />
       Execution time: %f sec<br/>
       Memory usage: %d Kb</p>',
       $validPermutationsCount,
       $stop,
       memory_get_peak_usage(true) / 1024);

如果有人有更好的主意，我就在这里！

【参考方案2】：

这就是您需要的。我根据需要发表了评论：

function permutations(array $array)

    switch (count($array)) 
        case 1:
            // Return the array as-is; returning the first item
            // of the array was confusing and unnecessary
            return $array;
            break;
        case 0:
            throw new InvalidArgumentException('Requires at least one array');
            break;
    

    // We 'll need these, as array_shift destroys them
    $keys = array_keys($array);

    $a = array_shift($array);
    $k = array_shift($keys); // Get the key that $a had
    $b = permutations($array);

    $return = array();
    foreach ($a as $v) 
        if(is_numeric($v))
        
            foreach ($b as $v2) 
                // array($k => $v) re-associates $v (each item in $a)
                // with the key that $a originally had
                // array_combine re-associates each item in $v2 with
                // the corresponding key it had in the original array
                // Also, using operator+ instead of array_merge
                // allows us to not lose the keys once more
                $return[] = array($k => $v) + array_combine($keys, $v2);
            
        
    

    return $return;

See it in action.

顺便说一句，递归地计算所有排列是很巧妙的，但您可能不想在生产环境中这样做。您绝对应该考虑进行健全性检查，以计算有多少排列，并且至少在它们超过某个限制时不允许继续处理。

【讨论】：

乔恩，感谢您的出色回应。我用示例数组进行了尝试，它完美地工作，但是，如果我使用这个数组，它会在 array_combine() 上引发错误： $traits = array ( '4' => array(7, 32), '8' = > 数组(4), '2' => 数组(9, 1), '12' => 数组(5, 78), '83' => 数组(10), '9' => 数组(3,67 ), );

当输入数组的最后一个元素包含 2 个或更多值时会出现问题。数组（3, 67）。我正在尝试修复它，但如果您找到解决方案，我将不胜感激。

【参考方案3】：

我通过将 Jon 的算法与我最初拥有的算法合并来改进了他的功能。我所做的是检查函数是否正在执行递归，如果是，我使用原始的 array_merge()（它正在工作），否则我使用 Jon 的 array_combine()（保留数组键）。

我将 Jon 的答案标记为正确，因为他提出了一个巧妙的解决方案来保持数组键的完整性。

function permutations(array $array, $inb=false)

    switch (count($array)) 
        case 1:
            // Return the array as-is; returning the first item
            // of the array was confusing and unnecessary
            return $array[0];
            break;
        case 0:
            throw new InvalidArgumentException('Requires at least one array');
            break;
    

    // We 'll need these, as array_shift destroys them
    $keys = array_keys($array);

    $a = array_shift($array);
    $k = array_shift($keys); // Get the key that $a had
    $b = permutations($array, 'recursing');

    $return = array();
    foreach ($a as $v) 
        if(is_numeric($v))
        
            foreach ($b as $v2) 
                // array($k => $v) re-associates $v (each item in $a)
                // with the key that $a originally had
                // array_combine re-associates each item in $v2 with
                // the corresponding key it had in the original array
                // Also, using operator+ instead of array_merge
                // allows us to not lose the keys once more
                if($inb == 'recursing')
                    $return[] = array_merge(array($v), (array) $v2);
                else
                    $return[] = array($k => $v) + array_combine($keys, $v2);
            
        
    

    return $return;

Tested successfully with several array combinations.