/*
* Encog(tm) Core v3.3 - Java Version
* http://www.heatonresearch.com/encog/
* https://github.com/encog/encog-java-core
* Copyright 2008-2014 Heaton Research, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* For more information on Heaton Research copyrights, licenses
* and trademarks visit:
* http://www.heatonresearch.com/copyright
*/
package org.encog.ml.bayesian.table;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;
import org.encog.Encog;
import org.encog.ml.bayesian.BayesianError;
import org.encog.ml.bayesian.BayesianEvent;
import org.encog.ml.bayesian.query.enumerate.EnumerationQuery;
/**
* Holds a Bayesian truth table.
*/
public class BayesianTable implements Serializable {
/**
* The event that owns this truth table.
*/
private final BayesianEvent event;
/**
* The lines of the truth table.
*/
private final List<TableLine> lines = new ArrayList<TableLine>();
public BayesianTable(BayesianEvent theEvent) {
this.event = theEvent;
reset();
}
/**
* Reset the truth table to zero.
*/
public void reset() {
this.lines.clear();
List<BayesianEvent> parents = this.event.getParents();
int l = parents.size();
int[] args = new int[l];
do {
for (int k = 0; k < event.getChoices().size(); k++) {
addLine(0, k, args);
}
} while (EnumerationQuery.roll(parents, args));
}
/**
* Add a new line.
* @param prob The probability.
* @param result The resulting probability.
* @param args The arguments.
*/
public void addLine(double prob, boolean result, boolean... args) {
int[] d = new int[args.length];
for (int i = 0; i < args.length; i++) {
d[i] = args[i] ? 0 : 1;
}
addLine(prob, result ? 0 : 1, d);
addLine(1.0 - prob, result ? 1 : 0, d);
}
/**
* Add a new line.
* @param prob The probability.
* @param result The resulting probability.
* @param args The arguments.
*/
public void addLine(double prob, int result, boolean... args) {
int[] d = new int[args.length];
for (int i = 0; i < args.length; i++) {
d[i] = args[i] ? 0 : 1;
}
addLine(prob, result, d);
}
/**
* Add a new line.
* @param prob The probability.
* @param result The resulting probability.
* @param args The arguments.
*/
public void addLine(double prob, int result, int... args) {
if (args.length != this.event.getParents().size()) {
throw new BayesianError("Truth table line with " + args.length
+ ", specied for event with "
+ this.event.getParents().size()
+ " parents. These numbers must be the same");
}
TableLine line = findLine(result, args);
if (line == null) {
if (this.lines.size() == this.getMaxLines()) {
throw new BayesianError("This truth table is already full.");
}
line = new TableLine(prob, result, args);
this.lines.add(line);
} else {
line.setProbability(prob);
}
}
/**
* Validate the truth table.
*/
public void validate() {
if (this.lines.size() != this.getMaxLines()) {
throw new BayesianError("Truth table for " + this.event.toString()
+ " only has " + this.lines
+ " line(s), should have " + this.getMaxLines()
+ " line(s).");
}
}
/**
* Generate a random sampling based on this truth table.
* @param args The arguemtns.
* @return The result.
*/
public int generateRandom(int... args) {
double r = Math.random();
double limit = 0;
for (TableLine line : this.lines) {
if (line != null && line.compareArgs(args)) {
limit += line.getProbability();
if (r < limit) {
return line.getResult();
}
}
}
throw new BayesianError("Incomplete logic table for event: "
+ this.event.toString());
}
/**
* {@inheritDoc}
*/
public String toString() {
StringBuilder result = new StringBuilder();
for (TableLine line : this.lines) {
result.append(line.toString());
result.append("\n");
}
return result.toString();
}
/**
* @return The lines of this truth table.
*/
public List<TableLine> getLines() {
return this.lines;
}
/**
* Find the specified truth table line.
* @param result The result sought.
* @param args The arguments.
* @return The line that matches.
*/
public TableLine findLine(int result, int[] args) {
for (TableLine line : this.lines) {
if (line != null && line.compareArgs(args)) {
if (Math.abs(line.getResult() - result) < Encog.DEFAULT_DOUBLE_EQUAL) {
return line;
}
}
}
return null;
}
/**
* @return The maximum number of lines this truth table would have.
*/
public int getMaxLines() {
return event.calculateParameterCount() * event.getChoices().size();
}
}