You have different methods to check whether a string is an empty string in Python. Like
>>> A = "" >>> A == "" True >>> A is "" True >>> not A True
The last method
not A is a Pythonic way recommended by Programming Recommendations in PEP8. By default, empty sequences and collections are evaluated as
False in a
not A is recommended not only because it is Pythonic, but also because it is the most efficient.
>>> timeit.timeit('A == ""', setup='A=""',number=10000000) 0.4620500060611903 >>> timeit.timeit('A is ""', setup='A=""',number=10000000) 0.36170379760869764 >>> timeit.timeit('not A', setup='A=""',number=10000000) 0.3231199442780053