Question

I’m just starting to learn Python and was playing around with the in operator in the interpreter and discovered something interesting. Why is this False:

# case 1
>>> [1] in [1,2,3]
False

but these are True?

# case 2
>>> [1] in [[1],2,3]
True

# case 3
>>> (1) in [(1),2,3]
True

# case 4
>>> (1) in [1,2,3]
True

# case 5
>>> 1 in [(1),2,3]
True

I can understand why #1 is False, since [1] is a list object and it does not occur in the list [1,2,3]. I also get why #2 is True. However, if tuples are immutable lists (as Norm Matloff describes them in his tutorial) or are immutable sequences (as the Python documentation for TUPLES says), why is (1) equated to 1 instead of [1]?

Answer 1

Brackets do not make a tuple, a comma does.

>>> (1)
1
>>> (1,)
(1,)

So where you do (1), it actually just means 1.

>>> (1,) in [1,2,3]
False