在两个值之间切换变量的大多数Python方法

Question

I have a variable, p, that is the output of a regular expression match and is guaranteed to be either 'true' or 'false' in any mixed case. If 'true' I want it to be 'FALSE' and if 'false' I want it to be 'TRUE'. The end result is always uppercase.

I have thought of the following four methods. Which is the most pythonic or is there a better one?

p=['TRUE','FALSE'][eval(p.capitalize())]
p=(not eval(p.capitalize())).__repr__().upper()
p='FALSE' if eval(p.capitalize()) else 'TRUE'
p={'TRUE':'FALSE','FALSE':'TRUE'}[p.upper()]

Answer 1

IMO, the most pythonic way isn't with eval , or with dunders, or using a 2-element list indexing, it's a simple if-else conditional (or ternary):

p = 'TRUE' if p.upper() == 'FALSE' else 'FALSE'

It doesn't use hacks or trickery, it is simple and (more importantly) readable.

Answer 2

@ cs95的解决方案是可行的方法，但这是（IMO）可接受的（尽管可读性较差，而且可能更复杂）替代方案：

p = str(p.upper() == "FALSE").upper()

Answer 3

EDITED:How about

p=str(p.lower()!="true").upper()

No loops, no if, no complex functions. Just change type functions. Short and simple ;)