防止列表理解被零除 [英] Preventing dividing by zero in list comprehensions

问题描述

我有以下代码:

scores = [matrix[i][i] / sum(matrix[i]) for (i, scores) in enumerate(matrix)]

我的问题是sum(matrix[i])在某些情况下可能为0，从而导致ZeroDivisionError.但是因为在这种情况下matrix[i][i]也是0，所以我如下解决了这个问题:

My problem is that sum(matrix[i]) could be 0 in some cases, resulting in a ZeroDivisionError. But because matrix[i][i] is also 0 in that case, I solved this as follows:

scores = [divide(matrix[i][i], sum(matrix[i])) for (i, scores) in enumerate(matrix)]

如果y == 0，函数divide(x, y)返回1，如果y > 0，则返回(x / y).但是我想知道是否有更简单的方法.也许我可以使用一些三元运算符，但是Python中存在吗?

The function divide(x, y) returns 1 if y == 0 and (x / y) if y > 0. But I wonder if there is an easier way. Maybe I could use some ternary operator, but does that exist in Python?

推荐答案

是的，在Python中，它称为条件表达式:

Yes, in Python it's called the conditional expression:

[matrix[i][i] / sum(matrix[i]) if sum(matrix[i]) != 0 else 0 
 for (i, scores) in enumerate(matrix)]

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