corr.writable.PearsonComputationWritable.java Source code

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Here is the source code for corr.writable.PearsonComputationWritable.java

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/**
 * Copyright 2012 Jee Vang 
 * 
 * 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. 
 */
package corr.writable;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import org.apache.hadoop.io.Writable;

/**
 * Holds intermediary results of Pearson correlation.
 * @author Jee Vang
 *
 */
public class PearsonComputationWritable implements Writable {

    private double xy;
    private double x;
    private double y;
    private double n;
    private double xx;
    private double yy;

    /**
     * Constructor.
     */
    public PearsonComputationWritable() {
        this(0.0d, 0.0d, 0.0d, 0.0d, 0.0d, 0.0d);
    }

    /**
     * Constructor.
     * @param x Sum of x.
     * @param y Sum of y.
     * @param xx Sum of x * y.
     * @param yy Sum of y * y.
     * @param xy Sum of x * y.
     * @param n Total data points.
     */
    public PearsonComputationWritable(double x, double y, double xx, double yy, double xy, double n) {
        this.x = x;
        this.y = y;
        this.xx = xx;
        this.yy = yy;
        this.xy = xy;
        this.n = n;
    }

    @Override
    public int hashCode() {
        return 37 + (new Double(x)).hashCode() + (new Double(y)).hashCode() + (new Double(xx)).hashCode()
                + (new Double(yy)).hashCode() + (new Double(xy)).hashCode() + (new Double(n)).hashCode();
    }

    @Override
    public void readFields(DataInput in) throws IOException {
        x = in.readDouble();
        y = in.readDouble();
        xx = in.readDouble();
        yy = in.readDouble();
        xy = in.readDouble();
        n = in.readDouble();
    }

    @Override
    public void write(DataOutput out) throws IOException {
        out.writeDouble(getX());
        out.writeDouble(getY());
        out.writeDouble(getXX());
        out.writeDouble(getYY());
        out.writeDouble(getXY());
        out.writeDouble(getN());
        out.writeDouble(getCorrelation());
    }

    @Override
    public String toString() {
        return (new StringBuilder()).append('{').append(x).append(',').append(y).append(',').append(xx).append(',')
                .append(yy).append(',').append(xy).append(',').append(n).append(',').append(getCorrelation())
                .append('}').toString();
    }

    /**
     * Gets the computed Pearson correlation.
     * @return Pearson correlation.
     */
    public double getCorrelation() {
        if (0.0d == n)
            return 0.0d;

        double numerator = x / n;
        numerator = numerator * y;
        numerator = xy - numerator;

        double denom1 = Math.pow(x, 2.0d) / n;
        denom1 = xx - denom1;

        double denom2 = Math.pow(y, 2.0d) / n;
        denom2 = yy - denom2;

        double denom = denom1 * denom2;
        denom = Math.sqrt(denom);

        double r = numerator / denom;
        return r;
    }

    /**
     * Gets sum of x * y.
     * @return double.
     */
    public double getXY() {
        return xy;
    }

    /**
     * Sets sum of x * y.
     * @param xy double.
     */
    public void setXY(double xy) {
        this.xy = xy;
    }

    /**
     * Gets sum of x.
     * @return double.
     */
    public double getX() {
        return x;
    }

    /**
     * Sets sum of x.
     * @param x double.
     */
    public void setX(double x) {
        this.x = x;
    }

    /**
     * Gets sum of y.
     * @return double.
     */
    public double getY() {
        return y;
    }

    /**
     * Sets sum of y.
     * @param y double.
     */
    public void setY(double y) {
        this.y = y;
    }

    /**
     * Gets total.
     * @return double.
     */
    public double getN() {
        return n;
    }

    /**
     * Sets total.
     * @param n double.
     */
    public void setN(double n) {
        this.n = n;
    }

    /**
     * Gets sum of x * x.
     * @return double.
     */
    public double getXX() {
        return xx;
    }

    /**
     * Sets sum of x * x.
     * @param xx double.
     */
    public void setXX(double xx) {
        this.xx = xx;
    }

    /**
     * Gets sum of y * y.
     * @return double.
     */
    public double getYY() {
        return yy;
    }

    /**
     * Sets sum of y * y.
     * @param yy double.
     */
    public void setYY(double yy) {
        this.yy = yy;
    }

}