[BangPypers] Would pypy result in a recast of what are the more efficient pythonic idioms ?

[chetan giridhar]

Out of curiosity ran the code in Python 3.2 and Python 2.7.

Python 2.7: 30 μsec
Python 3.2: 35 μsec

Regards,
Chetan


On Thu, Aug 11, 2011 at 3:47 PM, Dhananjay Nene <dhananjay.nene at gmail.com>wrote:

> I had done some benchmarking of code in various languages 3 years ago. I
> had
> not chosen to implement either the most efficient code, instead preferring
> to stick to a specific style of implementation. (The experiment is
> documented at
>
> http://blog.dhananjaynene.com/2008/07/performance-comparison-c-java-python-ruby-jython-jruby-groovy/
> )
>
> Curiously I revisited it today and tried it with pypy. The results were
> most
> remarkable.
>
> The python code as mentioned today required 112 μseconds on cPython 2.6
> while it ended up requiring only 4.4 μseconds on PyPy (1.5 alpha).
>
> What was even more curious was if one wrote the code differently eg. the
> following alternative implementation as suggested in one of the comments.
>
> def findlast(chainlength = 40, kill = 3):
>    firstinc, c = 1, range(1,chainlength + 1)
>    while len(c)>1:
>        c, firstinc = [x for n,x in enumerate(c) if (firstinc+n) % 3], (n+1
> + firstinc) %3
>    return c
>
> import time
> ITER = 100000
> print findlast()
> start = time.time()
> for i in range(ITER):
>    findlast()
> end = time.time()
> print 'Time per iteration = %s microseconds ' % ((end - start) * 1000000 /
> ITER)
>
> This code times in at about 31 μsec on cPython 2.6 vs 7.45 μseconds on PyPy
>
> So - the code that was 4 times faster on cPython is now 60% as fast on
> PyPy.
> Assuming more examples like this show up - I would imagine the definition
> of
> efficient pythonic idiom to be evolving rather fast in a different
> direction
> as pypy catches traction.
>
> Dhananjay
>
> --
>
> ----------------------------------------------------------------------------------------------------------------------------------
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-- 
Regards,
Chetan
http://technobeans.com