On Jun 28, 2006, at 10:02 AM, Stefan Wappler wrote:



> I'm interested in initializing the initial population by using  

> randomly generated individuals at the one hand (using grow, half,  

> or uniform), and by reusing individuals from previous optimizations  

> on the other hand. Is this basically possible? Is there any  

> documentation about seeding?



Not much, but we're here.  What do you want to know?



It works like this:

1. ECJ cals Initializer.initialPopulation(...)

2. Initializer.initialPopulation(...) calls Population.populate(...)

3. Population(...) calls Subpopulation.populate(...)

4. Subpopulation.populate(...) either generates random individuals or  

loads from a file



All you have to do is make a subclass of Subpopulation, override the  

populate method to fill the subpopulation as you like, and set the  

parameter pop.subpop.n=your.new.SubpopulationClassname for each  

subpopulation n that your'e using (likely you're only using one, so n  

would be 0).  The existing code in Subpopulation.populate(...) is  

small and easy to understand.  Use it to roll your own.



> As far as I know, when specifying pop.subpop.0.file=$myFile the  

> initial population will be created from the individuals from the  

> given file. Why is it important to have the fitness value also  

> saved to this file? The current optimization could use a different  

> fitness function and hence this value would be irrelevant.



Because ECJ doesn't know if you need the fitness or not.  Almost  

certainly you *will* need the fitness, so throwing it out would be  

unwelcome.  In the case that you want a different fitness, you can  

just replace it on initialization; override  

Initializer.initialPopulation(...) to call super, and then change the  

fitness as you like.



> Furthermore, I'd like to have an initial population containing 50  

> individuals. The seeding file contains only 10 individuals. How can  

> I specify that the remaining 40 individuals shall be generated  

> using a built-in tree builder (such as grow)?



You can't: you'll need to write that code, but it's easy.  See the  

discussion above.



Sean