Nick Coghlan wrote:
[EMAIL PROTECTED] wrote:
Nick> $ ./python -m timeit "'' % ()"
Nick> 1000000 loops, best of 3: 0.389 usec per loop
vs.
Nick> $ ./python -m timeit "'%s' % 'nothing'"
Nick> 10000000 loops, best of 3: 0.0736 usec per loop
I think you need to use a tuple for the second case to make it
comparable to
the first.
It doesn't actually make that big a difference - I'm guessing a
Py_INCREF shortcut ends up getting used either way:
$ ./python -m timeit "'%s' % 'nothing'"
10000000 loops, best of 3: 0.0848 usec per loop
$ ./python -m timeit "'%s' % 'nothing',"
10000000 loops, best of 3: 0.133 usec per loop
Technically there you aren't using a tuple to provide the substitution
argument, you are doing the substitution from a single string then
putting the result in a tuple:
>>> '%s' % 'nothing',
('nothing',)
>>>
On the basis of evidence like this:
[EMAIL PROTECTED] ~
$ python -m timeit "'%s' % 'nothing'"
10000000 loops, best of 3: 0.0705 usec per loop
[EMAIL PROTECTED] ~
$ python -m timeit "'%s' % ('nothing',)"
1000000 loops, best of 3: 0.691 usec per loop
I'd say not using a tuple was the way to go if ever you needed to
optimize the code for speed.
$ ./python -m timeit "'' % ()"
1000000 loops, best of 3: 0.513 usec per loop
If you want an even stranger result, it appears to take the interpreter
longer to substitute nothing from a tuple than it does to substitute the
empty string from a string:
[EMAIL PROTECTED] ~
$ python -m timeit "'' % ()"
1000000 loops, best of 3: 0.454 usec per loop
[EMAIL PROTECTED] ~
$ python -m timeit "'%s' % ''"
10000000 loops, best of 3: 0.0715 usec per loop
(times are a bit variable at this very moment since I have a few
different apps open)
Me too. Timings are not benchmarks, I am not a lawyer, etc. Our machines
seem to be of comparable speed.
regards
Steve
--
Steve Holden +1 571 484 6266 +1 800 494 3119
Holden Web LLC http://www.holdenweb.com/
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