根据PHP中的长度对多维数组进行排序

问题描述

我有一个函数，可以找到数组的所有可能组合:

I have a function that finds all the possible combinations of an array:

function combination($array)
{
    $results = array(array());

    foreach ($array as $element)
        foreach ($results as $combination)
            array_push($results, array_merge(array($element), $combination));

    return $results;
}

这将返回一个多维数组，并且可以正常工作.

This returns a multidimensional array and it works.

如果我尝试打印阵列，请使用以下命令:

If I try to print the array, I use this:

foreach (combination($set)  as $combination)
{
    print join("\t", $combination) . "  - ";
}

针对:$set = array('s','f','g');

输出为:- s - f - f s - g - g s - g f - g f s -

现在我不知道的是如何根据长度对组合进行排序，使输出变为:- g f s - g s - g f - f s - g - s - f -

Now what I cant figure out is how can I sort the combinations according to length in a way where the output becomes: - g f s - g s - g f - f s - g - s - f -

推荐答案

您需要为此使用'usort':

you need to use 'usort' for this:

function sortByLength($a, $b) {
    return count($b) - count($a);
}

$result = combination($set);

usort($result, 'sortByLength');

如果只使用一次，您也可以仅将'sortByLength'用作匿名函数，而不是对其进行定义:

you could also just use 'sortByLength' as an anonymous function, instead of defining it, if you use this only once:

$result = combination($set);

usort($result, function($a, $b) {
    return count($b) - count($a);
} );

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