Question

>>> {x for x in 'spam'}
{'a', 'p', 's', 'm'}

Why does it change the order? If you take a look at a loop, it works perfectly:

>>> for x in 'spam':
...     print(x)
... 
s
p
a
m
>>> 

Answer 1

Sets in python (and in set theory) are not ordered. So when you loop over them, there is no defined ordering.

You looped over the string literal 'spam' to make a set containing each character in that string. Once you did that, the ordering was gone.

When you perform the for loop over 'spam', you are performing the loop against a string which does have ordering.