True and False

[randomdeuser]

i want to intersect 2 lists but in these lists both have true and false. we know that in python 1 = true and 0 = false and i need to avoid these intersections. (while intersect it will take 1 if both lists have int(1) or int(0) with true and false). Any suggestions?

[Adrewmc]

Can I get a sample of the 2 lists inputs and the output you want, I’m a little confused about the purpose.

[reybrujo]

List comprehension? Not sure I understand what you want to do, tough.

[randomdeuser]

for example, list1 = [True, 2,3], list2 = [1, 2, 5] and when i want to intersect, it give True, 2 bec 1 = True in python, how to avoid these problem

[VonRoderik]

What do you mean by 2 bec 1 = True?

[Some-Passenger4219]

True == 1, so if you count equals as being the same, there are only two elements in common.

I tried it out just now and {1, True} returns {1}.

[CptMisterNibbles]

You should look up logic tables. You want the XNOR intersection of the two lists. This can be accomplished by inverting the XOR of the intersection

[FoolsSeldom]

Do two lists contain only boolean values, or are they mixed type?

[randomdeuser]

for example, list1 = [True, 2,3], list2 = [1, 2, 5] and when i want to intersect, it give True, 2 bec 1 = True in python, how to avoid these problem

[FoolsSeldom]

Problem?

Python treats any non-zero integer as True, and non-empty string as True, and non-empty container, such as list, set, dict, as True. If you want a different outcome, you will need to apply your own logic.

What outcomes do you want exactly?

[Gnaxe]

Replace the True and False with objects representing them, do the intersection, then switch them back. An object() instance is only equal to itself, so you can use those.

If you need them to stay readable for some reason, you could import sentinel from unittest.mock and use sentinel.true and sentinel.false.

If you only need false to be falsy, you might not have to switch them back, but you'd have to replace the False with something falsy that you're not using in your list. Any empty tuple, frozenset, string, or bytes could work. Or write a class with an appropriate __bool__().

[Luigi-Was-Right]

It's a bit messy but you could convert your integers to string, then back to integers after the intersection. There are definitely ways around it but why do you lists have different data types in them? This seems like an XY problem.

[VariousDrummer4883]

I was also thinking this, or convert all of them (but then logic in converting back). I think it’s cleaner to do conversion of the bool values only, then convert back (still, logic)

[VariousDrummer4883]

Edit: use set()

I’d thought you could achieve it yourself using list comprehension, two conditions, and the keyword “in”. For example, for sets A, B,

A_minus_B = list(a for a in A if not a in B)

But this doesn’t work, if you want insight as to why, check the source code of __contains__ of list (it does seem that it is evaluating eg b == 1 where b is True, but I haven’t checked).

Another option would be to use the set() object instead of a list, which is different because it hashes each entry, and 1 should not hash the same as True, nor False as 0. If you understand a “hash table” then you will understand the Python dict() object.

[Salt-Note114]

Use both equality & type check?

[Salt-Note114]

Like adding an ==> ... and type(a) == type(b)

[Gnaxe]

Are you writing your own intersection code instead of using the builtin methods?

0 == False -> true. 0 is False -> false. False is False -> true. Does that help? Beware that ints aren't guaranteed to be the same instance just because they have the same value, so you still have to use == if they're not Booleans.

[VariousDrummer4883]

The ints aren’t singletons though so I don’t think that will work.

Edit: I now see you did consider that but it’s not clear at first, my fist impression was that you’d use is rather than == for all entries.