A more pythonic way of writting

[eric]

On Dec 6, 12:19 am, Steven D'Aprano <st... at REMOVE-THIS-
cybersource.com.au> wrote:
> On Fri, 05 Dec 2008 07:44:21 -0800, eric wrote:
> > I like to believe that the less the 'debug pointer' stands in the python
> > code, the fastest the code is (or is potentially)
>
> What's a debug pointer?
>
> Pre-mature optimization is the root of evil in programming. Unless you
> have actually *measured* the speed of the code, how do you know you
> aren't making it slower instead of faster?
>
> Experience with other languages often is misleading when programming with
> Python. If you are used to programming in C, for example, then you will
> tend to program one way because comparisons are fast and moving records
> is slow. But in Python, comparisons can be slow and moving records is
> fast, so the C programmer's intuitions about "fast code" are often
> pessimations instead of optimizations.
>
> --
> Steven

you are right about premature optimization. I cannot disagree.

My 'rule of thumb' was more about that:
1/ keep the code the more descriptive and the less procedural as
possible.
2/ the less instructions you write, the more optimization you'll get
from the others

the hypercube function is cool, and I would use it, if I weren't in
charge of maintaining the code.


I've done some 'timeit'

import timeit

t1 = timeit.Timer(
                    """
                    h1 = hypercube(6)
                    """,
                    """def hypercube(ndims):
                        return [[i&mask==mask for mask in [1<<j for j
in range(ndims)] ] for i in range(1<<ndims)]""")

t2 = timeit.Timer(
                    """
                    h2 = [h for h in  hypercube(6)]
                    """,
                    """def hypercube(ndims):
                         if ndims == 0:
                             yield ()
                             return
                         for h in False,True:
                             for y in hypercube(ndims-1):
                                 yield (h,)+y""")

M= 100000
array_method = t1.timeit(M)
recursion_method = t2.timeit(M)

print "array method %s"%array_method
print "recursion method %s"%recursion_method

print "recursion is %s%% slower"%( (recursion_method - array_method)/
recursion_method*100)

"""
console result
array method 41.2270488739
recursion method 48.3009829521
recursion is 14.6455281981% slower
"""

well, nothing drastic here.