What is the pythonic way to determine that two or more boolean evaluations are all False?

Question

In a conditional like if (bool) and (bool):, what is the cleanest expression that will return True if both evaluations are False?

I see many options to logically make this work, but they all look messy to me.

Did you read https://stackoverflow.com/questions/16522111/python-syntax-for-if-a-or-b-or-c-but-not-all-of-them ? It seems to have good examples — B. Go, Sep 23 '19 at 00:04
if (not bool1) and (not bool2) should work, as if not (bool1 or bool2) — B. Go, Sep 23 '19 at 00:05
Possible duplicate of [Python syntax for "if a or b or c but not all of them"](https://stackoverflow.com/questions/16522111/python-syntax-for-if-a-or-b-or-c-but-not-all-of-them) — MyNameIsCaleb, Sep 23 '19 at 00:05
@B.Go, yes. Those are the best options I've seen. Thank you. — øøø, Sep 23 '19 at 00:24
@MyNameIsCaleb, the answer from the link you gave does apply to my question, but the question from that link is not as specific as mine. — øøø, Sep 23 '19 at 01:19

DjaouadNM · Answer 1 · 2019-09-23T13:57:35.723

0

You can either use all:

if all(not b for b in [bool_1, bool_2, ..., bool_n]):
# means: if all are not True (False)

any:

if not any([bool_1, bool_2, ..., bool_n]):
# means: if not any of them is True (same as above, logically)

Or, sum (only with bool type, otherwise use sum(map(bool, [bool_1, ..., bool_n]))):

if sum([bool_1, bool_2, ..., bool_n]) == 0:   #  or, if not sum(...):
# True is 1, False is 0, if sum is 0, then all are 0 (False)

edited Sep 23 '19 at 13:57

answered Sep 23 '19 at 00:05

DjaouadNM

I haven't tried `all` or `any` yet. Thank you. Those look very useful. – øøø Sep 23 '19 at 00:26
1

You don't need the genexp with `any`. – user2357112 Sep 23 '19 at 00:52
1

Note that those are not necessarily equivalent. `not (a or b)` will only evaluate `b` is `a` is `False`, whereas `not any(a, b)` will always evaluate both `a` and `b`. – tobias_k Sep 23 '19 at 14:10
@tobias_k you're right, but I meant (and said) _logically_ equivalent, which they are. – DjaouadNM Sep 23 '19 at 14:12

1 Answers1