ex11.c

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/* ----------------------------------------------------------------------------
  ex11.C
  mbwall 13apr95
  Copyright (c) 1995-1996  Massachusetts Institute of Technology

 DESCRIPTION:
   This example shows how to use an order-based list genome.
---------------------------------------------------------------------------- */
#include <stdio.h>
#include <stdlib.h>
#include <iostream.h>
#include <fstream.h>
#include <ga/ga.h>


// The objective function tells how good a genome is.  The Initializer defines
// how the lists should be initialized.
float objective(GAGenome &);
void ListInitializer(GAGenome &);


int
main(int argc, char *argv[])
{
  cout << "Example 11\n\n";
  cout << "This program illustrates the use of order-based lists.  The\n";
  cout << "list in this problem contains 25 numbers, 0 to 24.  It tries\n";
  cout << "to put them in descending order from 24 to 0.\n\n";
  cout.flush();

// See if we've been given a seed to use (for testing purposes).  When you
// specify a random seed, the evolution will be exactly the same each time
// you use that seed number.

  for(int ii=1; ii<argc; ii++) {
    if(strcmp(argv[ii++],"seed") == 0) {
      GARandomSeed((unsigned int)atoi(argv[ii]));
    }
  }

// Set the default values of the parameters.

  GAParameterList params;
  GASteadyStateGA::registerDefaultParameters(params);
  params.set(gaNpopulationSize, 30);	// population size
  params.set(gaNpCrossover, 0.6);	// probability of crossover
  params.set(gaNpMutation, 0.01);	// probability of mutation
  params.set(gaNnGenerations, 1000);	// number of generations
  params.set(gaNpReplacement, 0.5);	// how much of pop to replace each gen
  params.set(gaNscoreFrequency, 10);	// how often to record scores
  params.set(gaNnReplacement, 4);	// how much of pop to replace each gen
  params.set(gaNflushFrequency, 10);	// how often to dump scores to file
  params.set(gaNscoreFilename, "bog.dat");
//  params.read("settings.txt");	        // grab values from file first
  params.parse(argc, argv, gaFalse); // parse command line for GAlib args

// Now create the GA and run it.  We first create a genome with the
// operators we want.  Since we're using a template genome, we must assign
// all three operators.  We use the order-based crossover site when we assign
// the crossover operator.

  GAListGenome<int> genome(objective);
  genome.initializer(ListInitializer);
  genome.mutator(GAListGenome<int>::SwapMutator);

// Now that we have our genome, we create the GA (it clones the genome to 
// make all of the individuals for its populations).  Set the parameters on 
// the GA then let it evolve.

  GASteadyStateGA ga(genome);
  ga.crossover(GAListGenome<int>::PartialMatchCrossover);
  ga.parameters(params);
  ga.evolve();

// Assign the best that the GA found to our genome then print out the results.

  genome = ga.statistics().bestIndividual();
  cout << "the ga generated the following list (objective score is ";
  cout << genome.score() << "):\n" << genome << "\n";
  cout << "best of generation data are in '" << ga.scoreFilename() << "'\n";
  cout << ga.parameters() << "\n";

//  char *fn;
//  ga.get(gaNscoreFilename, &fn);
//  cout << "filename is '" << fn << "'\n";

  return 0;
}
 


/* ----------------------------------------------------------------------------
Objective function
  The objective function gives one point for every number in the correct
position.  We're trying to get a sequence of numbers from n to 0 in descending
order.
---------------------------------------------------------------------------- */
float
objective(GAGenome & c)
{
  GAListGenome<int> & genome = (GAListGenome<int> &)c;

  float score = (*genome.head() == genome.size()-1); // move to head of list
  for(int i=genome.size()-2; i>0; i--)
    score += (*genome.next() == i); // cycle through list and look at nodes
  return score;
}



/* ----------------------------------------------------------------------------
List Genome Operators
-------------------------------------------------------------------------------
The initializer creates a list with n elements in it and puts a unique digit
in each one.  After we make the list, we scramble everything up.
---------------------------------------------------------------------------- */
void
ListInitializer(GAGenome & c)
{
  GAListGenome<int> &child=(GAListGenome<int> &)c;
  while(child.head()) child.destroy(); // destroy any pre-existing list

  int n=25;
  child.insert(0,GAListBASE::HEAD); // the head node contains a '0'
  for(int i=1; i<n; i++)
    child.insert(i);		// each subsequent node contains a number
  for(int j=0; j<n; j++)
    child.swap(GARandomInt(0,n-1), GARandomInt(0,n-1));
}




//   Here we specialize the write method for the List class.  This lets us see
// exactly what we want (the default write method dumps out pointers to the
// data rather than the data contents).
//   This routine prints out the contents of each element of the list, 
// separated by a space.  It does not put a newline at the end of the list.
//   Notice that you can specialize ANY function of a template class, but 
// some compilers are more finicky about how you do it than others.  For the
// metrowerks compiler this specialization must come before the forced
// instantiation.
int
GAListGenome<int>::write(ostream & os) const
{
  int *cur, *head;
  GAListIter<int> tmpiter(*this);
  if((head=tmpiter.head()) != 0) os << *head << " ";
  for(cur=tmpiter.next(); cur && cur != head; cur=tmpiter.next())
    os << *cur << " ";
  return os.fail() ? 1 : 0;
}




// If your compiler does not do automatic instantiation (e.g. g++ 2.6.8),
// then define the NO_AUTO_INST directive.
#ifdef NO_AUTO_INST
#include <ga/GAList.C>
#include <ga/GAListGenome.C>
#if defined(__GNUG__)
template class GAList<int>;
template class GAListGenome<int>;
#else
GAList<int>;
GAListGenome<int>;
#endif
#endif