private void addMutantToDB(
Individual original, Individual mutant, int generationNumber, Location location) {
final GraphDatabaseService graphDB = GraphDB.graphDB();
IndexManager index = graphDB.index();
Index<Node> individualNodes = index.forNodes("individuals");
Index<Node> locationNodes = index.forNodes("locations");
Transaction tx = graphDB.beginTx();
Relationship mutantRelationship;
Relationship node;
Node individualNode;
try {
individualNode = graphDB.createNode();
individualNode.setProperty("fitness", mutant.getGlobalFitness());
individualNode.setProperty("id", mutant.uid.toString());
Node locationNode = locationNodes.get("locationID", location.getPosition()).next();
node = individualNode.createRelationshipTo(locationNode, RelTypes.LOCATEDIN);
node.setProperty("generation", generationNumber);
Node originalNode = individualNodes.get("id", original.uid.toString()).next();
mutantRelationship = individualNode.createRelationshipTo(originalNode, RelTypes.MUTANTOF);
mutantRelationship.setProperty("generation", generationNumber);
individualNodes.add(individualNode, "id", mutant.uid.toString());
tx.success();
} finally {
tx.finish();
}
}
@Override
protected double doEvaluation(Problem problem, Individual individual) {
OnesMaxProblem onesMaxProblem = (OnesMaxProblem) problem;
int numBits = onesMaxProblem.getBitStringSize();
if (numBits == 0) {
return 1.0;
}
int onesCount = 0;
int[] bits = individual.getBits();
for (int i = 0; i < numBits; i++) {
if (bits[i] == 1) {
onesCount++;
}
}
return onesCount / (double) numBits;
}
@Override
public Individual mutate(Individual ind, Object... parameters) {
int generationNumber = (Integer) parameters[1];
Location location = (Location) parameters[0];
int[] bits = ind.getBits();
double mutationRate = DoubleParameter.AVERAGE_MUTATIONS.getValue() / bits.length;
for (int i = 0; i < bits.length; i++) {
if (prngInstance.nextDouble() < mutationRate) {
bits[i] = flipBit(bits[i]);
}
}
Individual mutant = new Individual(bits);
addMutantToDB(ind, mutant, generationNumber, location);
return mutant;
}