> > You have to stop spending so much time playing with all this bogus
> > benchmarking :)
>
> It not bogus :) Its an example to find the best method for a project.
>
And I'll reiterate more clearly. Benchmarking is *not* the tool to find
the best method.
The BEST method for a project is that method which is self evident and
maintainable. ONLY AFTER you determine that you have missed your
performance envelope, do you go back through your code using rakes and
shovels and implements of destruction to find the slow parts. Early
Optimization Is The Root of All Evil.
> If you prefer I'll ask the question I was trying to answer with the
> benchmark:
>
> Assuming you have an array of 0-15 elements is it quicker/more efficient to:
>
> 1) create a hash slice and use exists when checking for specific ones
> or
> 2) grep a regex out of the array when checking for specific ones
>
Both. Each one will 'win' in terms of total execution time for some
set of conditions, none of which have been expressed in the problem.
(For example, will the keys always be small integers? How complex
will they be? This will have a tremendous impact on the performance
of the match operator.)
And, in fact, you yourself may not know a priori what the conditions
will be - which is why I say (again because you really need to hear
this): "Premature Optimization Is The Root of All Evil."
Write your code so you can maintain it. The microseconds will take
care of themselves. The programmers' time is orders of magnitude more
costly than the computers', and your value is (hopefully!) increasing,
while the cost of computational "oomph" is (thankfully) decreasing.
Now, as to this specific question -- use whichever idiom you are more
comfortable with. Furthermore, that is a tiny implementation detail
-- in the Big Picture, it won't matter a gnats eyebrow.
Finally, there were serious errors in your methodology in your
original benchmark. It turns out the printing dominated the total
execution time, such that the variance between the two different
selection methods were pushed down into the noise. When I benchmarked
using lists of 10 elements searching for five random members in
the list, the exists-in-hash version was about 10 times faster
for *JUST THE SELECTION OPERATION* than the grep-the-list version.
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
Lawrence Statton - [EMAIL PROTECTED] s/aba/c/g
Computer software consists of only two components: ones and
zeros, in roughly equal proportions. All that is required is to
sort them into the correct order.
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