samoa-api/src/main/java/org/apache/samoa/moa/core/DoubleVector.java

package org.apache.samoa.moa.core;

/*
 * #%L
 * SAMOA
 * %%
 * Copyright (C) 2014 - 2015 Apache Software Foundation
 * %%
 * 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.
 * #L%
 */

import org.apache.samoa.moa.AbstractMOAObject;

/**
 * Vector of double numbers with some utilities.
 * 
 * @author Richard Kirkby (rkirkby@cs.waikato.ac.nz)
 * @version $Revision: 7 $
 */
public class DoubleVector extends AbstractMOAObject {

  private static final long serialVersionUID = 1L;

  protected double[] array;

  public DoubleVector() {
    this.array = new double[0];
  }

  public DoubleVector(double[] toCopy) {
    this.array = new double[toCopy.length];
    System.arraycopy(toCopy, 0, this.array, 0, toCopy.length);
  }

  public DoubleVector(DoubleVector toCopy) {
    this(toCopy.getArrayRef());
  }

  public int numValues() {
    return this.array.length;
  }

  public void setValue(int i, double v) {
    if (i >= this.array.length) {
      setArrayLength(i + 1);
    }
    this.array[i] = v;
  }

  public void addToValue(int i, double v) {
    if (i >= this.array.length) {
      setArrayLength(i + 1);
    }
    this.array[i] += v;
  }

  public void addValues(DoubleVector toAdd) {
    addValues(toAdd.getArrayRef());
  }

  public void addValues(double[] toAdd) {
    if (toAdd.length > this.array.length) {
      setArrayLength(toAdd.length);
    }
    for (int i = 0; i < toAdd.length; i++) {
      this.array[i] += toAdd[i];
    }
  }

  public void subtractValues(DoubleVector toSubtract) {
    subtractValues(toSubtract.getArrayRef());
  }

  public void subtractValues(double[] toSubtract) {
    if (toSubtract.length > this.array.length) {
      setArrayLength(toSubtract.length);
    }
    for (int i = 0; i < toSubtract.length; i++) {
      this.array[i] -= toSubtract[i];
    }
  }

  public void addToValues(double toAdd) {
    for (int i = 0; i < this.array.length; i++) {
      this.array[i] = this.array[i] + toAdd;
    }
  }

  public void scaleValues(double multiplier) {
    for (int i = 0; i < this.array.length; i++) {
      this.array[i] = this.array[i] * multiplier;
    }
  }

  // returns 0.0 for values outside of range
  public double getValue(int i) {
    return ((i >= 0) && (i < this.array.length)) ? this.array[i] : 0.0;
  }

  public double sumOfValues() {
    double sum = 0.0;
    for (double element : this.array) {
      sum += element;
    }
    return sum;
  }

  public int maxIndex() {
    int max = -1;
    for (int i = 0; i < this.array.length; i++) {
      if ((max < 0) || (this.array[i] > this.array[max])) {
        max = i;
      }
    }
    return max;
  }

  public void normalize() {
    scaleValues(1.0 / sumOfValues());
  }

  public int numNonZeroEntries() {
    int count = 0;
    for (double element : this.array) {
      if (element != 0.0) {
        count++;
      }
    }
    return count;
  }

  public double minWeight() {
    if (this.array.length > 0) {
      double min = this.array[0];
      for (int i = 1; i < this.array.length; i++) {
        if (this.array[i] < min) {
          min = this.array[i];
        }
      }
      return min;
    }
    return 0.0;
  }

  public double[] getArrayCopy() {
    double[] aCopy = new double[this.array.length];
    System.arraycopy(this.array, 0, aCopy, 0, this.array.length);
    return aCopy;
  }

  public double[] getArrayRef() {
    return this.array;
  }

  protected void setArrayLength(int l) {
    double[] newArray = new double[l];
    int numToCopy = this.array.length;
    if (numToCopy > l) {
      numToCopy = l;
    }
    System.arraycopy(this.array, 0, newArray, 0, numToCopy);
    this.array = newArray;
  }

  public void getSingleLineDescription(StringBuilder out) {
    getSingleLineDescription(out, numValues());
  }

  public void getSingleLineDescription(StringBuilder out, int numValues) {
    out.append("{");
    for (int i = 0; i < numValues; i++) {
      if (i > 0) {
        out.append("|");
      }
      out.append(StringUtils.doubleToString(getValue(i), 3));
    }
    out.append("}");
  }

  @Override
  public void getDescription(StringBuilder sb, int indent) {
    getSingleLineDescription(sb);
  }
}