按日期列对多维数组进行排序，如果日期相同则使用其他列值 [英] Sort multidimensional array by date column, then use other column values if dates are the same

问题描述

我有一个存储人的多维数组.

I have a multidimensional array that stores people.

Array (
   id93294 => array (
       Name => "Tom Anderson",
       Birthday => "03/17/1975",
       Hometown => 'St. Louis',
       CurrentLocation => 'Mars'
   ),
   id29349 => (array (
       Name => "Tom Anderson",
       Birthday => "03/17/1975",
       Hometown => 'New York',
       CurrentLocation => 'New York'
   )
)

有点像，除了为人们提供更多信息，所以我想首先按生日排序，然后按另一个属性排序(如果他们的家乡与他们当前的位置匹配)但是一旦我对数组进行第二次排序，它就会丢失我使用生日做的第一类......

Kind of like that except with more info for the people, so I want to first sort by birthdays THEN sort by another attribute (if their hometown matches their current location) but once I do the second sort on the array it loses the first sort I did using the birthdays...

如何多次排序而不影响我之前的排序.

How do I sort multiple times without it messing up my previous sorts.

附言我正在使用 uasort.

P.S. I am using uasort.

推荐答案

更新

我最近回答在有关对多维数组进行排序的确定性"主题中，以更有效的方式解决了这个问题.您可以安全地跳过阅读本答案的其余部分，直接点击链接以获取更强大的解决方案.

Update

I recently answered this question in a much more capable manner in the "definitive" topic on sorting multidimensional arrays. You can safely skip reading the rest of this answer and directly follow the link for a much more capable solution.

函数 uasort 允许您定义自己的比较函数.只需将您想要的所有标准放入其中.

The function uasort lets you define your own comparison function. Simply put all the criteria you want inside that.

例如，先按生日然后按姓名排序:

For example, to sort by birthday and then by name:

function comparer($first, $second) {
    // First see if birthdays differ
    if ($first['birthday'] < $second['birthday']) {
        return -1;
    }
    else if ($first['birthday'] > $second['birthday']) {
        return 1;
    }

    // OK, birthdays are equal. What else?
    if ($first['name'] < $second['name']) {
        return -1;
    }
    else if ($first['name'] > $second['name']) {
        return 1;
    }

    // No more sort criteria. The two elements are equal.
    return 0;
}

我忽略了这样一个事实，即在您的示例中，生日不是可以通过使用运算符 < 进行简单比较来排序的格式.在实践中，您会先将它们转换为简单可比的格式.

I am ignoring the fact that in your example, the birthdays are not in a format that can be ordered by a simple comparison using the operator <. In practice you would convert them to a trivially-comparable format first.

更新:如果你认为维护一堆这些多标准比较器会很快变得丑陋，你会发现我同意.但是这个问题可以像计算机科学中的任何其他问题一样解决:只需添加另一个抽象级别.

Update: if you think that maintaining a bunch of these multiple-criteria comparers could get ugly real fast, you find me in agreement. But this problem can be solved as any other in computer science: just add another level of abstraction.

我将在下一个示例中假设 PHP 5.3，以便使用方便的 anon 函数语法.但原则上，你可以用 create_function 做同样的事情.

I 'll be assuming PHP 5.3 for the next example, in order to use the convenient anon function syntax. But in principle, you could do the same with create_function.

function make_comparer() {
    $criteriaNames = func_get_args();
    $comparer = function($first, $second) use ($criteriaNames) {
        // Do we have anything to compare?
        while(!empty($criteriaNames)) {
            // What will we compare now?
            $criterion = array_shift($criteriaNames);

            // Do the actual comparison
            if ($first[$criterion] < $second[$criterion]) {
                return -1;
            }
            else if ($first[$criterion] > $second[$criterion]) {
                return 1;
            }

        }

        // Nothing more to compare with, so $first == $second
        return 0;
    };

    return $comparer;
}

然后你可以这样做:

uasort($myArray, make_comparer('birthday', 'name'));

这个例子可能太聪明了；一般来说，我不喜欢使用不按名称接受参数的函数.但在这种情况下，使用场景是过于聪明的有力论据.

This example possibly tries to be too clever; in general I don't like to use functions that do not accept their arguments by name. But in this case, the usage scenario is a very strong argument for being too clever.

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