package com.rapidminer.operator.learner.functions;
import com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.operator.learner.SimplePredictionModel;
import com.rapidminer.tools.Tools;
public class PolynomialRegressionModel extends SimplePredictionModel {
private static final long serialVersionUID = 5503523600824976254L;
private String[] attributeNames;
private double[][] coefficients;
private double[][] degrees;
private double offset;
public PolynomialRegressionModel(ExampleSet exampleSet, double[][] coefficients, double[][] degrees, double offset) {
super(exampleSet);
this.attributeNames = com.rapidminer.example.Tools.getRegularAttributeNamesOrConstructions(exampleSet);
this.coefficients = coefficients;
this.degrees = degrees;
this.offset = offset;
}
public double predict(Example example) throws OperatorException {
return calculatePrediction(example, coefficients, degrees, offset);
}
public static double calculatePrediction(Example example, double[][] coefficients, double[][] degrees, double offset) {
double prediction = 0;
int index = 0;
for (Attribute attribute : example.getAttributes()) {
double value = example.getValue(attribute);
for (int f = 0; f < coefficients.length; f++) {
prediction += coefficients[f][index] * Math.pow(value, degrees[f][index]);
}
index++;
}
prediction += offset;
return prediction;
}
public String toString() {
StringBuffer result = new StringBuffer();
boolean first = true;
int index = 0;
for (int i = 0; i < attributeNames.length; i++) {
for (int f = 0; f < coefficients.length; f++) {
result.append(getCoefficientString(coefficients[f][index], first) + " * " + attributeNames[i] + " ^ " + Tools.formatNumber(degrees[f][i]) + Tools.getLineSeparator());
first = false;
}
index++;
}
result.append(getCoefficientString(offset, first));
return result.toString();
}
private String getCoefficientString(double coefficient, boolean first) {
if (!first) {
if (coefficient >= 0)
return "+ " + Tools.formatNumber(Math.abs(coefficient));
else
return "- " + Tools.formatNumber(Math.abs(coefficient));
} else {
if (coefficient >= 0)
return " " + Tools.formatNumber(Math.abs(coefficient));
else
return "- " + Tools.formatNumber(Math.abs(coefficient));
}
}
}