[galib] GA doesn't evaluate all mutated individuals

Daniel Marbach daniel.marbach at epfl.ch
Tue Nov 23 12:54:50 EST 2004


I'm using galib to co-evoleve configuration and control of modular robots. At
the beginning I was very happy with galib, but by now I must say that I spent
more time studying the library and customizing stuff than it would have taken to
implement the GA from scratch. But that's just because I customize/extend almost
everything (Genome, selection, replacement, scaling, mutation...), I believe
galib can be highly beneficial for users with more 'standard' genomes.

I had a problem that cost me a lot of time - I don't know if it is a bug in
galib or if I
did something wrong:

For a long time, the performance of my GA (a GASteadyStateGA) was not very good
and weird things happened (e.g. weak individuals had a high fitness). By
coincidence I discovered, that the GA was not always evaluating all the
individuals that mutated. Adding the following lines to my mutation function
solved the

if (nMut > 0)
   _evaluated = gaFalse;

Shouldn't galib do that for me? Or what did I do wrong that I had to add these

Thanks for your help,

PS: My genome class extends GATreeGenome<GARealGenome>.

Daniel Marbach
Bitziusstr. 9
CH-3006 Bern

Tel: 031 351 11 09
WWW: http://icwww.epfl.ch/~marbach/

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