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339 lines
6.6 KiB
C++
339 lines
6.6 KiB
C++
//
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// FILE: RunningAverage.cpp
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// AUTHOR: Rob Tillaart
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// VERSION: 0.4.3
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// DATE: 2015-July-10
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// PURPOSE: Arduino library to calculate the running average by means of a circular buffer
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// URL: https://github.com/RobTillaart/RunningAverage
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//
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// The library stores N individual values in a circular buffer,
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// to calculate the running average.
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#include "RunningAverage.h"
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RunningAverage::RunningAverage(const uint16_t size)
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{
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_size = size;
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_partial = _size;
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_array = (float*) malloc(_size * sizeof(float));
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if (_array == NULL) _size = 0;
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clear();
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}
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RunningAverage::~RunningAverage()
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{
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if (_array != NULL) free(_array);
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}
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// resets all counters
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void RunningAverage::clear()
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{
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_count = 0;
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_index = 0;
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_sum = 0.0;
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_min = NAN;
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_max = NAN;
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for (uint16_t i = _size; i > 0; )
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{
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_array[--i] = 0.0; // keeps addValue simpler
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}
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}
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// adds a new value to the data-set
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void RunningAverage::addValue(const float value)
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{
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if (_array == NULL)
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{
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return;
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}
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_sum -= _array[_index];
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_array[_index] = value;
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_sum += _array[_index];
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_index++;
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if (_index == _partial) _index = 0; // faster than %
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// handle min max
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if (_count == 0) _min = _max = value;
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else if (value < _min) _min = value;
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else if (value > _max) _max = value;
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// update count as last otherwise if ( _count == 0) above will fail
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if (_count < _partial) _count++;
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}
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// returns the average of the data-set added so far, NAN if no elements.
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float RunningAverage::getAverage()
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{
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if (_count == 0)
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{
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return NAN;
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}
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// OPTIMIZE local variable for sum.
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_sum = 0;
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for (uint16_t i = 0; i < _count; i++)
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{
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_sum += _array[i];
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}
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return _sum / _count; // multiplication is faster ==> extra admin
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}
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// the larger the size of the internal buffer
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// the greater the gain wrt getAverage()
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float RunningAverage::getFastAverage() const
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{
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if (_count == 0)
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{
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return NAN;
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}
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return _sum / _count; // multiplication is faster ==> extra admin
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}
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// returns the minimum value in the buffer
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float RunningAverage::getMinInBuffer() const
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{
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if (_count == 0)
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{
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return NAN;
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}
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float _min = _array[0];
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for (uint16_t i = 1; i < _count; i++)
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{
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if (_array[i] < _min) _min = _array[i];
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}
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return _min;
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}
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// returns the maximum value in the buffer
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float RunningAverage::getMaxInBuffer() const
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{
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if (_count == 0)
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{
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return NAN;
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}
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float _max = _array[0];
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for (uint16_t i = 1; i < _count; i++)
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{
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if (_array[i] > _max) _max = _array[i];
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}
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return _max;
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}
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// returns the value of an element if exist, NAN otherwise
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float RunningAverage::getElement(uint16_t index) const
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{
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if (_count == 0)
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{
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return NAN;
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}
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return _array[index];
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}
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// Return standard deviation of running average.
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// If buffer is empty or has only one element, return NAN.
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float RunningAverage::getStandardDeviation() const
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{
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// see issue #13
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// need float _stddev = -1;
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// + patch add() and clear() to reset _stddev to -1;
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// if (_stddev != -1) return _stddev;
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if (_count <= 1) return NAN;
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float temp = 0;
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float average = getFastAverage();
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for (uint16_t i = 0; i < _count; i++)
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{
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temp += pow((_array[i] - average), 2);
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}
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temp = sqrt(temp/(_count - 1));
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return temp;
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// see issue #13
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// _stddev = temp; // cache the calculate value
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// return _stddev;
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}
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// Return standard error of running average.
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// If buffer is empty or has only one element, return NAN.
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float RunningAverage::getStandardError() const
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{
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float temp = getStandardDeviation();
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if (temp == NAN) return NAN;
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float n;
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if (_count >= 30) n = _count;
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else n = _count - 1;
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temp = temp/sqrt(n);
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return temp;
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}
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// fill the average with the same value number times. (weight)
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// This is maximized to size times.
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// no need to fill the internal buffer over 100%
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void RunningAverage::fillValue(const float value, const uint16_t number)
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{
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clear();
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uint16_t s = number;
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if (s > _partial) s = _partial;
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for (uint16_t i = s; i > 0; i--)
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{
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addValue(value);
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}
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}
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// https://github.com/RobTillaart/RunningAverage/issues/13
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// - substantially faster version off fillValue()
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// - adds to program size
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// void RunningAverage::fillValue(const float value, const uint16_t number)
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// {
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// uint16_t s = number;
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// if (s > _partial) s = _partial;
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// for (uint16_t i = 0; i < s; i++)
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// {
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// _array[i] = value;
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// }
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// _min = value;
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// _max = value;
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// _sum = value * s;
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// _count = s;
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// _index = s;
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// if (_index == _partial) _index = 0;
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// }
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float RunningAverage::getValue(const uint16_t position)
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{
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if (_count == 0)
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{
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return NAN;
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}
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if (position >= _count)
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{
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return NAN; // cannot ask more than is added
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}
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uint16_t _pos = position + _index;
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if (_pos >= _count) _pos -= _count;
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return _array[_pos];
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}
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void RunningAverage::setPartial(const uint16_t partial)
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{
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_partial = partial;
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if ((_partial == 0) || (_partial > _size)) _partial = _size;
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clear();
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}
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////////////////////////////////////////////////////////////////
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//
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// 0.4.1 added.
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//
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float RunningAverage::getAverageLast(uint16_t count)
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{
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uint16_t cnt = count;
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if (cnt > _count) cnt = _count;
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if (cnt == 0) return NAN;
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uint16_t idx = _index;
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float _sum = 0;
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for (uint16_t i = 0; i < cnt; i++)
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{
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if (idx == 0) idx = _size;
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idx--;
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_sum +=_array[idx];
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}
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return _sum / cnt;
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}
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float RunningAverage::getMinInBufferLast(uint16_t count)
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{
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uint16_t cnt = count;
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if (cnt > _count) cnt = _count;
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if (cnt == 0) return NAN;
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uint16_t idx = _index;
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if (idx == 0) idx = _size;
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idx--;
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float _min = _array[idx];
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for (uint16_t i = 0; i < cnt; i++)
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{
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if (_array[idx] < _min) _min = _array[idx];
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if (idx == 0) idx = _size;
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idx--;
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}
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return _min;
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}
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float RunningAverage::getMaxInBufferLast(uint16_t count)
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{
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uint16_t cnt = count;
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if (cnt > _count) cnt = _count;
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if (cnt == 0) return NAN;
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uint16_t idx = _index;
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if (idx == 0) idx = _size;
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idx--;
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float _max = _array[idx];
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for (uint16_t i = 0; i < cnt; i++)
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{
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if (_array[idx] > _max) _max = _array[idx];
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if (idx == 0) idx = _size;
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idx--;
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}
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return _max;
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}
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////////////////////////////////////////////////////////////////
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//
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// Experimental 0.4.3
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//
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float RunningAverage::getAverageSubset(uint16_t start, uint16_t count)
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{
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if (_count == 0)
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{
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return NAN;
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}
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uint16_t cnt = _count;
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if (cnt > count) cnt = count;
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float sum = 0; // do not disrupt global _sum
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for (uint16_t i = 0; i < cnt; i++)
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{
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uint16_t idx = _index + start + i;
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while (idx >= _partial) idx -= _partial;
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sum += _array[idx];
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}
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return sum / cnt;
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}
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// -- END OF FILE --
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