python how to "negate" value : if true return false, if false return true

Question

if myval == 0:
   nyval=1
if myval == 1:
   nyval=0

Is there a better way to do a toggle in python, like a nyvalue = not myval ?

Answer 1

Use the not boolean operator:

nyval = not myval

not returns a boolean value (True or False):

>>> not 1
False
>>> not 0
True

If you must have an integer, cast it back:

nyval = int(not myval)

However, the python bool type is a subclass of int, so this may not be needed:

>>> int(not 0)
1
>>> int(not 1)
0
>>> not 0 == 1
True
>>> not 1 == 0
True

Answer 2

In python, not is a boolean operator which gets the opposite of a value:

>>> myval = 0
>>> nyvalue = not myval
>>> nyvalue
True
>>> myval = 1
>>> nyvalue = not myval
>>> nyvalue
False

And True == 1 and False == 0 (if you need to convert it to an integer, you can use int())

Answer 3

Use not, for example:

return not myval

Answer 4

variable = not (False | variable)

is similar to

if variable == True:
    variable = False
elif variable == False:
    variable = True