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/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see .
 */

/*
 *    DoubleVector.java
 *    Copyright (C) 2002-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.core.matrix;

import java.lang.reflect.Method;
import java.util.Arrays;

import weka.core.RevisionHandler;
import weka.core.RevisionUtils;

/**
 * A vector specialized on doubles.
 * 
 * @author Yong Wang
 * @version $Revision: 10203 $
 */
public class DoubleVector implements Cloneable, RevisionHandler {

  double[] V; // array for internal storage of elements.

  private int sizeOfVector; // size of the vector

  /*
   * ------------------------ Constructors ------------------------
   */

  /**
   * Constructs a null vector.
   */
  public DoubleVector() {
    this(0);
  }

  /**
   * Constructs an n-vector of zeros.
   * 
   * @param n length.
   */
  public DoubleVector(int n) {
    V = new double[n];
    setSize(n);
  }

  /**
   * Constructs a constant n-vector.
   * 
   * @param n length.
   * @param s the scalar value used to fill the vector
   */
  public DoubleVector(int n, double s) {
    this(n);
    set(s);
  }

  /**
   * Constructs a vector directly from a double array
   * 
   * @param v the array
   */
  public DoubleVector(double v[]) {
    if (v == null) {
      V = new double[0];
      setSize(0);
    } else {
      V = v;
      setSize(v.length);
    }
  }

  /*
   * ------------------------ Public Methods ------------------------
   */

  /**
   * Set a single element.
   * 
   * @param i Index.
   * @param s a[i].
   */
  public void set(int i, double s) {

    V[i] = s;
  }

  /**
   * Set all elements to a value
   * 
   * @param s the value
   */
  public void set(double s) {
    set(0, size() - 1, s);
  }

  /**
   * Set some elements to a value
   * 
   * @param i0 the index of the first element
   * @param i1 the index of the second element
   * @param s the value
   */
  public void set(int i0, int i1, double s) {

    for (int i = i0; i <= i1; i++) {
      V[i] = s;
    }
  }

  /**
   * Set some elements using a 2-D array
   * 
   * @param i0 the index of the first element
   * @param i1 the index of the second element
   * @param j0 the index of the starting element in the 2-D array
   * @param v the values
   */
  public void set(int i0, int i1, double[] v, int j0) {
    for (int i = i0; i <= i1; i++) {
      V[i] = v[j0 + i - i0];
    }
  }

  /**
   * Set the elements using a DoubleVector
   * 
   * @param v the DoubleVector
   */
  public void set(DoubleVector v) {
    set(0, v.size() - 1, v, 0);
  }

  /**
   * Set some elements using a DoubleVector.
   * 
   * @param i0 the index of the first element
   * @param i1 the index of the second element
   * @param v the DoubleVector
   * @param j0 the index of the starting element in the DoubleVector
   */
  public void set(int i0, int i1, DoubleVector v, int j0) {
    for (int i = i0; i <= i1; i++) {
      V[i] = v.V[j0 + i - i0];
    }
  }

  /**
   * Access the internal one-dimensional array.
   * 
   * @return Pointer to the one-dimensional array of vector elements.
   */
  public double[] getArray() {
    return V;
  }

  void setArray(double[] a) {
    V = a;
  }

  /**
   * Returns a copy of the DoubleVector usng a double array.
   * 
   * @return the one-dimensional array.
   */
  public double[] getArrayCopy() {
    double v[] = new double[size()];

    for (int i = 0; i < size(); i++) {
      v[i] = V[i];
    }

    return v;
  }

  /** Sorts the array in place */
  public void sort() {
    Arrays.sort(V, 0, size());
  }

  /** Sorts the array in place with index returned */
  public IntVector sortWithIndex() {
    IntVector index = IntVector.seq(0, size() - 1);
    sortWithIndex(0, size() - 1, index);
    return index;
  }

  /**
   * Sorts the array in place with index changed
   * 
   * @param xi first index
   * @param xj last index
   * @param index array that stores all indices
   */
  public void sortWithIndex(int xi, int xj, IntVector index) {
    if (xi < xj) {
      double x;
      int xm = (xi + xj) / 2; // median index
      x = Math.min(V[xi], // median of three
        Math.max(V[xm], V[xj]));
      int i = xi;
      int j = xj;
      while (i < j) {
        while (V[i] < x && i < xj) {
          i++;
        }
        while (V[j] > x && j > xi) {
          j--;
        }
        if (i <= j) {
          swap(i, j);
          index.swap(i, j);
          i++;
          j--;
        }
      }
      sortWithIndex(xi, j, index);
      sortWithIndex(i, xj, index);
    }
  }

  /**
   * Gets the size of the vector.
   * 
   * @return the size
   */
  public int size() {
    return sizeOfVector;
  }

  /**
   * Sets the size of the vector
   * 
   * @param m the size
   */
  public void setSize(int m) {
    if (m > capacity()) {
      throw new IllegalArgumentException("insufficient capacity");
    }
    sizeOfVector = m;
  }

  /**
   * Gets the capacity of the vector.
   * 
   * @return the capacity.
   */
  public int capacity() {
    if (V == null) {
      return 0;
    }
    return V.length;
  }

  /**
   * Sets the capacity of the vector
   * 
   * @param n the capacity.
   */
  public void setCapacity(int n) {
    if (n == capacity()) {
      return;
    }
    double[] oldV = V;
    int m = Math.min(n, size());
    V = new double[n];
    setSize(m);
    set(0, m - 1, oldV, 0);
  }

  /**
   * Gets a single element.
   * 
   * @param i Index.
   * @return the value of the i-th element
   */
  public double get(int i) {
    return V[i];
  }

  /**
   * Adds a value to an element
   * 
   * @param i the index of the element
   * @param s the value
   */
  public void setPlus(int i, double s) {
    V[i] += s;
  }

  /**
   * Multiplies a value to an element
   * 
   * @param i the index of the element
   * @param s the value
   */
  public void setTimes(int i, double s) {
    V[i] *= s;
  }

  /**
   * Adds an element into the vector
   * 
   * @param x the value of the new element
   */
  public void addElement(double x) {
    if (capacity() == 0) {
      setCapacity(10);
    }
    if (size() == capacity()) {
      setCapacity(2 * capacity());
    }
    V[size()] = x;
    setSize(size() + 1);
  }

  /**
   * Returns the squared vector
   */
  public DoubleVector square() {
    DoubleVector v = new DoubleVector(size());
    for (int i = 0; i < size(); i++) {
      v.V[i] = V[i] * V[i];
    }
    return v;
  }

  /**
   * Returns the square-root of all the elements in the vector
   */
  public DoubleVector sqrt() {
    DoubleVector v = new DoubleVector(size());
    for (int i = 0; i < size(); i++) {
      v.V[i] = Math.sqrt(V[i]);
    }
    return v;
  }

  /**
   * Makes a deep copy of the vector
   */
  public DoubleVector copy() {
    return (DoubleVector) clone();
  }

  /**
   * Clones the DoubleVector object.
   */
  @Override
  public Object clone() {
    int n = size();
    DoubleVector u = new DoubleVector(n);
    for (int i = 0; i < n; i++) {
      u.V[i] = V[i];
    }
    return u;
  }

  /**
   * Returns the inner product of two DoubleVectors
   * 
   * @param v the second DoubleVector
   * @return the product
   */
  public double innerProduct(DoubleVector v) {
    if (size() != v.size()) {
      throw new IllegalArgumentException("sizes unmatch");
    }
    double p = 0;
    for (int i = 0; i < size(); i++) {
      p += V[i] * v.V[i];
    }
    return p;
  }

  /**
   * Returns the signs of all elements in terms of -1, 0 and +1.
   */
  public DoubleVector sign() {
    DoubleVector s = new DoubleVector(size());
    for (int i = 0; i < size(); i++) {
      if (V[i] > 0) {
        s.V[i] = 1;
      } else if (V[i] < 0) {
        s.V[i] = -1;
      } else {
        s.V[i] = 0;
      }
    }
    return s;
  }

  /**
   * Returns the sum of all elements in the vector.
   */
  public double sum() {
    double s = 0;
    for (int i = 0; i < size(); i++) {
      s += V[i];
    }
    return s;
  }

  /**
   * Returns the squared sum of all elements in the vector.
   */
  public double sum2() {
    double s2 = 0;
    for (int i = 0; i < size(); i++) {
      s2 += V[i] * V[i];
    }
    return s2;
  }

  /**
   * Returns the L1-norm of the vector
   */
  public double norm1() {
    double s = 0;
    for (int i = 0; i < size(); i++) {
      s += Math.abs(V[i]);
    }
    return s;
  }

  /**
   * Returns the L2-norm of the vector
   */
  public double norm2() {
    return Math.sqrt(sum2());
  }

  /**
   * Returns ||u-v||^2
   * 
   * @param v the second vector
   */
  public double sum2(DoubleVector v) {
    return minus(v).sum2();
  }

  /**
   * Returns a subvector.
   * 
   * @param i0 the index of the first element
   * @param i1 the index of the last element
   * @return v[i0:i1]
   */
  public DoubleVector subvector(int i0, int i1) {
    DoubleVector v = new DoubleVector(i1 - i0 + 1);
    v.set(0, i1 - i0, this, i0);
    return v;
  }

  /**
   * Returns a subvector.
   * 
   * @param index stores the indices of the needed elements
   * @return v[index]
   */
  public DoubleVector subvector(IntVector index) {
    DoubleVector v = new DoubleVector(index.size());
    for (int i = 0; i < index.size(); i++) {
      v.V[i] = V[index.V[i]];
    }
    return v;
  }

  /**
   * Returns a vector from the pivoting indices. Elements not indexed are set to
   * zero.
   * 
   * @param index stores the pivoting indices
   * @param length the total number of the potential elements
   * @return the subvector
   */
  public DoubleVector unpivoting(IntVector index, int length) {
    if (index.size() > length) {
      throw new IllegalArgumentException("index.size() > length ");
    }
    DoubleVector u = new DoubleVector(length);
    for (int i = 0; i < index.size(); i++) {
      u.V[index.V[i]] = V[i];
    }
    return u;
  }

  /**
   * Adds a value to all the elements
   * 
   * @param x the value
   */
  public DoubleVector plus(double x) {
    return copy().plusEquals(x);
  }

  /**
   * Adds a value to all the elements in place
   * 
   * @param x the value
   */
  public DoubleVector plusEquals(double x) {
    for (int i = 0; i < size(); i++) {
      V[i] += x;
    }
    return this;
  }

  /**
   * Adds another vector element by element
   * 
   * @param v the second vector
   */
  public DoubleVector plus(DoubleVector v) {
    return copy().plusEquals(v);
  }

  /**
   * Adds another vector in place element by element
   * 
   * @param v the second vector
   */
  public DoubleVector plusEquals(DoubleVector v) {
    for (int i = 0; i < size(); i++) {
      V[i] += v.V[i];
    }
    return this;
  }

  /**
   * Subtracts a value
   * 
   * @param x the value
   */
  public DoubleVector minus(double x) {
    return plus(-x);
  }

  /**
   * Subtracts a value in place
   * 
   * @param x the value
   */
  public DoubleVector minusEquals(double x) {
    plusEquals(-x);
    return this;
  }

  /**
   * Subtracts another DoubleVector element by element
   * 
   * @param v the second DoubleVector
   */
  public DoubleVector minus(DoubleVector v) {
    return copy().minusEquals(v);
  }

  /**
   * Subtracts another DoubleVector element by element in place
   * 
   * @param v the second DoubleVector
   */
  public DoubleVector minusEquals(DoubleVector v) {
    for (int i = 0; i < size(); i++) {
      V[i] -= v.V[i];
    }
    return this;
  }

  /**
   * Multiplies a scalar
   * 
   * @param s scalar
   * @return s * v
   */
  public DoubleVector times(double s) {
    return copy().timesEquals(s);
  }

  /**
   * Multiply a vector by a scalar in place, u = s * u
   * 
   * @param s scalar
   * @return replace u by s * u
   */
  public DoubleVector timesEquals(double s) {
    for (int i = 0; i < size(); i++) {
      V[i] *= s;
    }
    return this;
  }

  /**
   * Multiplies another DoubleVector element by element
   * 
   * @param v the second DoubleVector
   */
  public DoubleVector times(DoubleVector v) {
    return copy().timesEquals(v);

  }

  /**
   * Multiplies another DoubleVector element by element in place
   * 
   * @param v the second DoubleVector
   */
  public DoubleVector timesEquals(DoubleVector v) {
    for (int i = 0; i < size(); i++) {
      V[i] *= v.V[i];
    }
    return this;
  }

  /**
   * Divided by another DoubleVector element by element
   * 
   * @param v the second DoubleVector
   */
  public DoubleVector dividedBy(DoubleVector v) {
    return copy().dividedByEquals(v);
  }

  /**
   * Divided by another DoubleVector element by element in place
   * 
   * @param v the second DoubleVector
   */
  public DoubleVector dividedByEquals(DoubleVector v) {
    for (int i = 0; i < size(); i++) {
      V[i] /= v.V[i];
    }
    return this;
  }

  /**
   * Checks if it is an empty vector
   */
  public boolean isEmpty() {
    if (size() == 0) {
      return true;
    }
    return false;
  }

  /**
   * Returns a vector that stores the cumulated values of the original vector
   */
  public DoubleVector cumulate() {
    return copy().cumulateInPlace();
  }

  /**
   * Cumulates the original vector in place
   */
  public DoubleVector cumulateInPlace() {
    for (int i = 1; i < size(); i++) {
      V[i] += V[i - 1];
    }
    return this;
  }

  /**
   * Returns the index of the maximum.
   * 
   * If multiple maximums exist, the index of the first is returned.
   */
  public int indexOfMax() {
    int index = 0;
    double ma = V[0];

    for (int i = 1; i < size(); i++) {
      if (ma < V[i]) {
        ma = V[i];
        index = i;
      }
    }
    return index;
  }

  /**
   * Returns true if vector not sorted
   */
  public boolean unsorted() {
    if (size() < 2) {
      return false;
    }
    for (int i = 1; i < size(); i++) {
      if (V[i - 1] > V[i]) {
        return true;
      }
    }
    return false;
  }

  /**
   * Combine two vectors together
   * 
   * @param v the second vector
   */
  public DoubleVector cat(DoubleVector v) {
    DoubleVector w = new DoubleVector(size() + v.size());
    w.set(0, size() - 1, this, 0);
    w.set(size(), size() + v.size() - 1, v, 0);
    return w;
  }

  /**
   * Swaps the values stored at i and j
   * 
   * @param i the index i
   * @param j the index j
   */
  public void swap(int i, int j) {
    if (i == j) {
      return;
    }
    double t = V[i];
    V[i] = V[j];
    V[j] = t;
  }

  /**
   * Returns the maximum value of all elements
   */
  public double max() {
    if (size() < 1) {
      throw new IllegalArgumentException("zero size");
    }
    double ma = V[0];
    if (size() < 2) {
      return ma;
    }
    for (int i = 1; i < size(); i++) {
      if (V[i] > ma) {
        ma = V[i];
      }
    }
    return ma;
  }

  /**
   * Applies a method to the vector
   * 
   * @param className the class name
   * @param method the method
   */
  public DoubleVector map(String className, String method) {
    try {
      Class c = Class.forName(className);
      Class[] cs = new Class[1];
      cs[0] = Double.TYPE;
      Method m = c.getMethod(method, cs);

      DoubleVector w = new DoubleVector(size());
      Object[] obj = new Object[1];
      for (int i = 0; i < size(); i++) {
        obj[0] = new Double(V[i]);
        w.set(i, Double.parseDouble(m.invoke(null, obj).toString()));
      }
      return w;
    } catch (Exception e) {
      e.printStackTrace();
      System.exit(1);
    }
    return null;
  }

  /**
   * Returns the reverse vector
   */
  public DoubleVector rev() {
    int n = size();
    DoubleVector w = new DoubleVector(n);
    for (int i = 0; i < n; i++) {
      w.V[i] = V[n - i - 1];
    }
    return w;
  }

  /**
   * Returns a random vector of uniform distribution
   * 
   * @param n the size of the vector
   */
  public static DoubleVector random(int n) {
    DoubleVector v = new DoubleVector(n);
    for (int i = 0; i < n; i++) {
      v.V[i] = Math.random();
    }
    return v;
  }

  /**
   * Convert the DoubleVecor to a string
   */
  @Override
  public String toString() {
    return toString(5, false);
  }

  /**
   * Convert the DoubleVecor to a string
   * 
   * @param digits the number of digits after decimal point
   * @param trailing true if trailing zeros are to be shown
   */
  public String toString(int digits, boolean trailing) {
    if (isEmpty()) {
      return "null vector";
    }

    StringBuffer text = new StringBuffer();
    FlexibleDecimalFormat nf = new FlexibleDecimalFormat(digits, trailing);
    nf.grouping(true);
    for (int i = 0; i < size(); i++) {
      nf.update(V[i]);
    }
    int count = 0;
    int width = 80;
    String number;
    for (int i = 0; i < size(); i++) {
      number = nf.format(V[i]);
      count += 1 + number.length();
      if (count > width - 1) {
        text.append('\n');
        count = 1 + number.length();
      }
      text.append(" " + number);
    }

    return text.toString();
  }

  /**
   * Returns the revision string.
   * 
   * @return the revision
   */
  @Override
  public String getRevision() {
    return RevisionUtils.extract("$Revision: 10203 $");
  }

  public static void main(String args[]) {

    DoubleVector v = random(10);
    DoubleVector a = random(10);
    DoubleVector w = a;

    System.out.println(random(10).plus(v).plus(w));

  }
}