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Re: Fast common substring matching

by GrandFather (Cardinal)
on Aug 26, 2005 at 23:11 UTC ( #487060=note: print w/ replies, xml ) Need Help??


in reply to Fast common substring matching

The following is a copy of Re^9: Fast common substring matching posted by bioMan, but the nesting was so deep I though I'd "bring it to the top".

I have done a quick test. Quick because of your blazing fast algorithm. My runtimes for 3 to 200 strings is given below. The times come from the Time::HiRes::gettimeofday function in your program. I set $subStrSize = 256.

3,0.001355 4,0.002366 5,0.003744 6,0.005187 7,0.006808 8,0.008807 9,0.011459 10,0.014172 11,0.017328 12,0.020473 13,0.023491 14,0.027905 15,0.031813 16,0.036426 17,0.043177 18,0.067228 19,0.052098 20,0.059449 30,0.132611 40,0.235241 50,0.367828 60,0.510851 70,0.695534 80,0.913879 90,1.178992 100,1.427899 125,2.254988 150,3.269179 200,5.831225

These results are from a second copy of your program that I created. It appears my first copy still has a bug.

Yes, there must be a bug in my original copy. Running my full data set with my backup copy of your program gave a runtime of 14.759568. I'd say that's a little better than three years! I'll check the results to see how they compare with some of my old results from limited data sets. That check could take a little time :-)

The problem could be with the way PerlIDE runs scripts. All the times above are from the command line (Win2000).

I ran the full data set with the second copy of the program from PerlIDE and got a runtime of 15.147881. So the problem is with my first copy of your program.

I really like your algorithm. It's speed will allow me to modify my original data and test a couple of theories. You've got a real winner.


Perl is Huffman encoded by design.


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