Swapping 1 with 0 and 0 with 1 in a Pythonic way

Question

In some part of my Python program I have a val variable that can be 1 or 0. If it\'s 1 I must change to 0, if it\'s 0 I must change to 1.

How do you do it in a Pytho

Answer 1

I have swapped 0s and 1s in a list.

Here's my list:

list1 = [1,0,0,1,0]

list1 = [i^1 for i in list1] 
#xor each element is the list

print(list1)

So the outcome is: [0,1,1,0,1]

Answer 2

If you want to be short:

f = lambda val: 0 if val else 1

Then:

>>> f(0)
1
>>> f(1)
0

Answer 3

This isn't pythonic, but it is language neutral. Often val = 1 - val is simplest.

Answer 4

Just another way:

val = ~val + 2

Answer 5

Just another possibility:

i = (1,0)[i]

This works well as long as i is positive, as dbr pointed out in the comments it doesn't work fail for i < 0.

Are you sure you don't want to use False and True? It sounds almost like it.

Answer 6

After seeing all these simpler answers i thought of adding an abstract one , it's Pythonic though :

val = set(range(0,2)).symmetric_difference(set(range(0 + val, val + 1))).pop()

All we do is return the difference of 2 sets namely [0, 1] and [val] where val is either 0 or 1.

we use symmetric_difference() to create the set [0, 1] - [val] and pop() to assign that value to variable val.