/thirdparty/liblastfm2/src/fingerprint/fplib/FloatingAverage.h

  1/*
  2   Copyright 2005-2009 Last.fm Ltd. <mir@last.fm>
  3
  4   This file is part of liblastfm.
  5
  6   liblastfm is free software: you can redistribute it and/or modify
  7   it under the terms of the GNU General Public License as published by
  8   the Free Software Foundation, either version 3 of the License, or
  9   (at your option) any later version.
 10
 11   liblastfm is distributed in the hope that it will be useful,
 12   but WITHOUT ANY WARRANTY; without even the implied warranty of
 13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14   GNU General Public License for more details.
 15
 16   You should have received a copy of the GNU General Public License
 17   along with liblastfm.  If not, see <http://www.gnu.org/licenses/>.
 18*/
 19#ifndef __FLOAT_AVERAGE_H__
 20#define __FLOAT_AVERAGE_H__
 21
 22//#include <deque>
 23#include <limits>
 24#include "CircularArray.h"
 25
 26template <typename T>
 27class FloatingAverage
 28{
 29public:
 30   FloatingAverage(size_t size)
 31   {
 32      m_values.resize(size);
 33      m_valIt = m_values.head();
 34      m_sum = 0;
 35      m_bufferFilled = false;
 36   }
 37
 38   void purge()
 39   {
 40      m_sum = 0;
 41      const T* pCircularBuffer = m_values.get_buffer();
 42      const int size = m_values.size();
 43
 44      for ( int i = 0; i < size; ++i )
 45         m_sum += pCircularBuffer[i];
 46   }
 47
 48   void add(const T& value)
 49   {
 50      m_sum += value;
 51
 52      if ( m_bufferFilled )
 53      {
 54         m_sum -= *m_valIt;
 55         *m_valIt = value;
 56         ++m_valIt;
 57      }
 58      else
 59      {
 60         *m_valIt = value;
 61         ++m_valIt;
 62         if ( m_valIt == m_values.head() )
 63            m_bufferFilled = true;
 64      }
 65   }
 66
 67   T getAverage() const
 68   {
 69      if ( !m_bufferFilled )
 70         return m_sum / (m_valIt - m_values.head());
 71      else
 72         return m_sum / m_values.size();
 73   }
 74
 75   T getError() const
 76   {
 77      T real_sum = 0;
 78      const T* pCircularBuffer = m_values.get_buffer();
 79      for ( int i = 0; i < size; ++i )
 80         real_sum += pCircularBuffer[i];
 81      return abs(real_sum - m_sum) / this->size();
 82   }
 83
 84   size_t size() const
 85   {
 86      return m_values.size();
 87   }
 88
 89   void clear()
 90   {
 91      m_bufferFilled = false;
 92      m_values.zero_fill();
 93      m_valIt = m_values.head();
 94      m_sum = 0;
 95   }
 96
 97private:
 98   //std::deque<T> m_values;
 99   CircularArray<T> m_values;
100   typename CircularArray<T>::iterator m_valIt;
101
102   bool m_bufferFilled;
103   T m_sum;
104};
105
106#endif // __FLOAT_AVERAGE_H__