if语句可以是变量吗？

Question

抱歉标题，我不知道我想做的事情的术语。

我有一个包含一系列嵌套循环的函数，它运行了很多次。循环有很多关于它们是继续还是重新开始的条件。

有时，调用此函数需要满足罕见的某些条件。但是，要检查它们，我需要在我的代码中添加更多 if 语句。

这是我正在谈论的例子，我函数中的一些循环：

while 1:

    for node in currset:

        for (sum1, weight1, l1, r1) in pathdict[(0, node)]:  
            if sum1 & sum != sum1 or r1 == left or r1 == right or l1 == left:
                continue

            if level < connectright:
                if l1 == right:
                    continue
            elif l1 != right:
                    continue

            for (sum2, weight2, l2, r2) in pathdict[(level, r1)]:
                if sum2&sum != sum2:
                    continue
                if l2 != left or l2 == right:
                    continue
                andsum = sum1&sum2

                if andsum != r1:
                    continue

现在，如果我遇到其中许多条件不再适用的特殊情况，我该怎么办？我现在的看法是，我可以 1.) 编写一个全新的函数，2.) 重写整个代码块并将其放在另一个 if 语句之后，3.) 添加一系列甚至更多的条件，或者 4. )编写一个函数来检查我在给定步骤的条件。

前两个选项看起来很笨重，但至少我的代码运行速度很快。第三个看起来很糟糕，因为代码变得难以阅读，而且速度变慢。第 4 个，我不确定，但似乎多次调用这些函数会减慢我的循环速度。

所以我的问题是，有没有什么方法可以写 "conditional if statements"，根据传递给函数的变量，我可以这样做：

if variable_passed == thing#1:
     my_if_statement = (if level < connectright:  continue)
else:
     my_if_statement = (if level > connectright:  continue)

这样我就可以在开始循环之前轻松更改函数开始时的条件。

Answer 1

您可以创建所有采用相同参数的函数列表，并使用参数的子集计算条件。

我觉得有点多，除非你有很多，或者正在创造条件。

一个例子：

outer = [  # lambda parameters are all that could be used in any expression at point of call
            (lambda sum, sum1, weight1, l1, r1, left, right, level, connectright:
                sum1 & sum != sum1 or r1 == left or r1 == right or l1 == left),
            (lambda sum, sum1, weight1, l1, r1, left, right, level, connectright:
                level < connectright),
            (lambda sum, sum1, weight1, l1, r1, left, right, level, connectright: 
                l1 != right),
        # ... add extra outer loop conditions as necessary
        ]
inner1 = [  # lambda parameters are all that could be used in any expression at point of call
            (lambda sum2, weight2, l2, r2, sum, sum1, weight1, l1, r1, left, right, level, connectright: 
                sum2&sum != sum2),
            (lambda sum2, weight2, l2, r2, sum, sum1, weight1, l1, r1, left, right, level, connectright: 
                l2 != left or l2 == right),
        # ... add extra inner loop conditions as necessary
        ]
inner2 = [  # lambda parameters are all that could be used in any expression at point of call
            (lambda andsum, sum2, weight2, l2, r2, sum, sum1, weight1, l1, r1, left, right, level, connectright: 
                andsum != r1),
        # ... add extra inner loop #2 conditions as necessary
        ]

while True:
    for node in currset:
        for (sum1, weight1, l1, r1) in pathdict[(0, node)]:  
            if any(f(sum, sum1, weight1, l1, r1, left, right, level, connectright)
                    for f in outer):
                continue
            for (sum2, weight2, l2, r2) in pathdict[(level, r1)]:
                if any(f(sum2, weight2, l2, r2, sum, sum1, weight1, l1, r1, left, right, level, connectright)
                        for f in inner1):
                    continue
                andsum = sum1&sum2
                if any(f(andsum, sum2, weight2, l2, r2, sum, sum1, weight1, l1, r1, left, right, level, connectright)
                        for f in inner2):
                    continue

if语句可以是变量吗？

Can an if statement be a variable?

python

algorithm

conditional

loops

if-statement