every element of list is True boolean

Question

I know that

all(map(compare,new_subjects.values()))==True

would tell me if every element of the list is True. However, how do I tell whether every element except for one of them is True?

Answer 1

values = map(compare, new_subjects.values())
len([x for x in values if x]) == len(values) - 1

Basically, you filter the list for true values and compare the length of that list to the original to see if it's one less.

Answer 2

If you mean is actually True and not evaluates to True, you can just count them?

>>> L1 = [True]*5
>>> L1
[True, True, True, True, True]
>>> L2 = [True]*5 + [False]*2
>>> L2
[True, True, True, True, True, False, False]
>>> L1.count(False)
0
>>> L2.count(False)
2
>>> 

checking for only a single False:

>>> def there_can_be_only_one(L):
...     return L.count(False) == 1
... 
>>> there_can_be_only_one(L1)
False
>>> there_can_be_only_one(L2)
False
>>> L3 = [ True, True, False ]
>>> there_can_be_only_one(L3)
True
>>> 

edit: This actually answer your question better:

>>> def there_must_be_only_one(L):
...     return L.count(True) == len(L)-1
... 
>>> there_must_be_only_one(L3)
True
>>> there_must_be_only_one(L2)
False
>>> there_must_be_only_one(L1)
False