“不等于”或“大于”更快吗？

Question

I wonder which of the following is done quicker for a tuple (also for a list or an int) :

a_tuple = ('a', 'b',)

1. if (len(a_tuple) != 0): pass

2. if (len(a_tuple) > 0): pass

I did some timeit experiment and the result is rather similar (vary each time I run timeit for 100000 iterations). I just wonder if there is a time benefit.

Answer 1

Use not a_tuple ( True if empty) or tuple ( True if not empty) instead of testing for the length:

if a_tuple:
    pass

Or, as a demonstration speaks louder than words:

>>> if not ():
...     print('empty!')
...
empty!
>>> if (1, 0):
...     print('not empty!')
...
not empty!

Apart from the fact that this is a micro optimization, testing for the falsy-ness of the empty tuple is faster too. When in doubt about speed, use the timeit module:

>>> import timeit
>>> a_tuple = (1,0)
>>> def ft_bool():
...     if a_tuple:
...         pass
... 
>>> def ft_len_gt():
...     if len(a_tuple) > 0:
...         pass
... 
>>> def ft_len_ne():
...     if len(a_tuple) != 0:
...         pass
... 
>>> timeit.timeit('ft()', 'from __main__ import ft_bool as ft')
0.17232918739318848
>>> timeit.timeit('ft()', 'from __main__ import ft_len_gt as ft')
0.2506139278411865
>>> timeit.timeit('ft()', 'from __main__ import ft_len_ne as ft')
0.23904109001159668