Why set in python not prints True, but prints False

Question

myset = {3, 4, 5, 1, 23, 45, 23, 89, "rohit", "raman", "rohit", 4, 5 , True, False,  3j}
print(myset)

# Output-
{False, 1, 3, 4, 5, 3j, 'raman', 45, 23, 89, 'rohit'}

My question is why its not printing "True" in output, but its printing "False". If it can print False then why not True?

Because in Python `1 == True` and you already have `1` in the set. — DallogFheir, Aug 04 '23 at 04:37
Does this answer your question? [Is False == 0 and True == 1 an implementation detail or is it guaranteed by the language?](https://stackoverflow.com/questions/2764017/is-false-0-and-true-1-an-implementation-detail-or-is-it-guaranteed-by-the) — InSync, Aug 04 '23 at 04:37

score 0 · Answer 1 · answered Aug 04 '23 at 04:46

For set and dict types in Python, the rule for seeing if a value already exists is if any value in the existing set or dict compares equal to the new value, i.e. if old_val == new_val is True. (It is assumed that such values will also have the same hash value.)

In this case, 1 and True compare as equal, i.e. 1 == True is True. When this happens, the old element is retained, including its type. Since 1 appeared before True, the set ends up containing 1 rather than True. If you reverse the order of the two elements, you'll end up with a set that contains True but not 1.

You can see a similar effect with 0 and False. Note that 0.0, 0j, etc. also compare equal to 0.

destructioneer · Answer 2 · 2023-08-04T04:54:24.467

Have a short look at the docs: A set object is an unordered collection of distinct hashable objects.

A set has to have unique members. And a set does not maintain an order.

Because of this, the doubled items 4, 5, "rohit" are kicked out. As True==1 the True is also kicked. The rest of your items are rearranged, and as False==0 it happens to be in first place, but with no guarantee that this will always be the case. If you add another element 0 with your set, preferably before False, the False will also be replaced.

Remember, in Python your boolean variables are kind of integers.

Why set in python not prints True, but prints False

2 Answers2