[galib] GA doesn't evaluate all mutated individuals

[christian hresko]

hmmm.  maybe there's a bug elsewhere in your code.  i just wrote my own 
mutation operator and it works perfectly.  i converge upon an optimal 
score and all the mean, min and max scores look correct.  i'm also 
using a GASteayStateGA.  are you sure something's not up with your 
objective function or your selection scheme?

christian

On Nov 28, 2004, at 3:57 PM, Daniel Marbach wrote:

>> You might be interested in the following thread on the same subject:
>>
>> http://mailman.mit.edu/pipermail/galib/1999-May/000145.html
>>
>
> Thanks, but the thread mentioned above discusses always evaluating all 
> the
> individuals - it is clear to me how to do that with evaluate(gaTrue) 
> (I studied
> the documentation...)
>
> I don't want to evaluate all the individuals, but only those that 
> mutated, i.e.
> those where the mutator returned a value greater than 0. When the 
> mutator
> returns 0, that means that nMut=0, i.e. the genome was not mutated. If 
> no
> crossover was used and no mutation occured, the individual should 
> obviously not
> be re-evaluated (waste of time), so evaulate(gaTrue) is not good in my 
> case.
>
> As I mentioned, I actually solved my problem by adding the following 
> lines to
> the mutation function of my genome:
>
>>> if (nMut > 0)
>>>   _evaluated = gaFalse;
>
> I was just wondering why the galib GA doesn't take care of this (or 
> what I did
> wrong so that it didn't re-evaluate mutated genomes...)
>
>
> Greetings,
>
>   Daniel
>
>
>
>> Daniel Marbach wrote:
>>
>>> Hi,
>>>
>>>
>>> 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
>>> problem:
>>>
>>> if (nMut > 0)
>>>   _evaluated = gaFalse;
>>>
>>> Shouldn't galib do that for me? Or what did I do wrong that I had to 
>>> add
>> these
>>> lines?
>>>
>>>
>>> Thanks for your help,
>>>   Daniel
>>>
>>> PS: My genome class extends GATreeGenome<GARealGenome>.
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