How to Check a String Is Empty in a Pythonic Way

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 Boolean context.

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