min_max.h

强大的C++库

/*!
 * \file
 * \brief Minimum and maximum functions on vectors and matrices
 * \author Tony Ottosson, Johan Bergman and Adam Piatyszek
 *
 * -------------------------------------------------------------------------
 *
 * IT++ - C++ library of mathematical, signal processing, speech processing,
 *        and communications classes and functions
 *
 * Copyright (C) 1995-2008  (see AUTHORS file for a list of contributors)
 *
 * 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 2 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, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 *
 * -------------------------------------------------------------------------
 */

#ifndef MIN_MAX_H
#define MIN_MAX_H

#include <itpp/base/mat.h>


namespace itpp {

  /*!
   * \addtogroup miscfunc
   * @{
   */

  //! Maximum value of vector
  template<class T>
  T max(const Vec<T> &v)
  {
    T maxdata = v(0);
    for (int i = 1; i < v.length(); i++)
      if (v(i) > maxdata)
	maxdata = v(i);
    return maxdata;
  }

  //! Maximum value of vector, also returns the index position of max value
  template<class T>
  T max(const Vec<T> &v, int& index)
  {
    T maxdata = v(0);
    index = 0;
    for (int i = 1; i < v.length(); i++)
      if (v(i) > maxdata) {
	maxdata = v(i);
	index = i;
      }
    return maxdata;
  }

  /*!
   * Maximum values over each row/column in the matrix \c m
   *
   * <tt>max(m) = max(m, 1)</tt> returns a vector where the elements are
   * maximum over each column, whereas <tt>max(m, 2)</tt> returns a vector
   * where the elements are maximum over each row.
   */
  template<class T>
  Vec<T> max(const Mat<T> &m, int dim = 1)
  {
    it_assert((dim == 1) || (dim == 2), "max(): dimension need to be 1 or 2");
    Vec<T> out;
    if (dim == 1) {
      out.set_size(m.cols(), false);
      for (int i = 0; i < m.cols(); i++)
	out(i) = max(m.get_col(i));
    }
    else {
      out.set_size(m.rows(), false);
      for (int i = 0; i < m.rows(); i++)
	out(i) = max(m.get_row(i));
    }
    return out;
  }

  /*!
   * Maximum values over each row/column in the matrix \c m
   *
   * <tt>max(m) = max(m, 1)</tt> returns a vector where the elements are
   * maximum over each column, whereas <tt>max(m, 2)</tt> returns a vector
   * where the elements are maximum over each row.
   *
   * Also returns a vector of indices with positions of maximum value within
   * a column/row.
   */
  template<class T>
  Vec<T> max(const Mat<T> &m, ivec &index, int dim = 1)
  {
    it_assert((dim == 1) || (dim == 2), "max(): dimension need to be 1 or 2");
    Vec<T> out;
    if (dim == 1) {
      out.set_size(m.cols(), false);
      index.set_size(m.cols(), false);
      for (int i = 0; i < m.cols(); i++)
	out(i) = max(m.get_col(i), index(i));
    }
    else {
      out.set_size(m.rows(), false);
      index.set_size(m.rows(), false);
      for (int i = 0; i < m.rows(); i++)
	out(i) = max(m.get_row(i), index(i));
    }
    return out;
  }

  //! Minimum value of vector
  template<class T>
  T min(const Vec<T> &in)
  {
    T mindata = in[0];
    for (int i = 1; i < in.length(); i++)
      if (in[i] < mindata)
	mindata = in[i];
    return mindata;
  }

  //! Minimum value of vector, also returns the index position of min value
  template<class T>
  T min(const Vec<T> &in, int& index)
  {
    T mindata = in[0];
    index = 0;
    for (int i = 1; i < in.length(); i++)
      if (in[i] < mindata) {
	mindata = in[i];
	index = i;
      }
    return mindata;
  }


  /*!
   * Minimum values over each row/column in the matrix \c m
   *
   * <tt>min(m) = min(m, 1)</tt> returns a vector where the elements are
   * minimum over each column, whereas <tt>min(m, 2)</tt> returns a vector
   * where the elements are minimum over each row.
   */
  template<class T>
  Vec<T> min(const Mat<T> &m, int dim=1)
  {
    it_assert((dim == 1) || (dim == 2), "min(): dimension need to be 1 or 2");
    Vec<T> out;
    if (dim == 1) {
      out.set_size(m.cols(), false);
      for (int i = 0; i < m.cols(); i++)
	out(i) = min(m.get_col(i));
    }
    else {
      out.set_size(m.rows(), false);
      for (int i = 0; i < m.rows(); i++)
	out(i) = min(m.get_row(i));
    }
    return out;
  }


  /*!
   * Minimum values over each row/column in the matrix \c m
   *
   * <tt>min(m) = min(m, 1)</tt> returns a vector where the elements are
   * minimum over each column, whereas <tt>min(m, 2)</tt> returns a vector
   * where the elements are minimum over each row.
   *
   * Also returns a vector of indices with positions of minimum value within
   * a column/row.
   */
  template<class T>
  Vec<T> min(const Mat<T> &m,  ivec &index, int dim=1)
  {
    it_assert((dim == 1) || (dim == 2), "min(): dimension need to be 1 or 2");
    Vec<T> out;
    if (dim == 1) {
      out.set_size(m.cols(), false);
      index.set_size(m.cols(), false);
      for (int i = 0; i < m.cols(); i++)
	out(i) = min(m.get_col(i), index(i));
    }
    else {
      out.set_size(m.rows(), false);
      index.set_size(m.rows(), false);
      for (int i = 0; i < m.rows(); i++)
	out(i) = min(m.get_row(i), index(i));
    }
    return out;
  }


  //! Return the postion of the maximum element in the vector
  template<class T>
  int max_index(const Vec<T> &in)
  {
    int	maxindex = 0;
    for (int i = 1; i < in.length(); i++)
      if (in[i] > in[maxindex])
	maxindex = i;
    return maxindex;
  }

  //! Return the postion of the maximum element in the matrix
  template<class T>
  void max_index(const Mat<T> &m, int &row, int &col)
  {
    T maxdata = m(0, 0);
    row = col = 0;
    for (int i = 0; i < m.rows(); i++)
      for (int j = 0; j < m.cols(); j++)
	if (m(i, j) > maxdata) {
	  row = i;
	  col = j;
	  maxdata = m(i, j);
	}
  }

  //! Return the postion of the minimum element in the vector
  template<class T>
  int min_index(const Vec<T> &in)
  {
    int minindex = 0;
    for (int i = 1; i < in.length(); i++)
      if (in[i] < in[minindex])
	minindex = i;
    return minindex;
  }

  //! Return the postion of the minimum element in the matrix
  template<class T>
  void min_index(const Mat<T> &m, int &row, int &col)
  {
    T mindata = m(0, 0);
    row = col = 0;
    for (int i = 0; i < m.rows(); i++)
      for (int j = 0; j < m.cols(); j++)
	if (m(i, j) < mindata) {
	  row = i;
	  col = j;
	  mindata = m(i, j);
	}
  }

  /*!
   * @}
   */

} //namespace itpp


#endif /* MIN_MAX_H */