moving_average.h

#pragma once
#include <vector>

class Filter {
public:
  virtual void add_entry(double n) = 0;
  virtual double get_value() const = 0;
};

class MovingAverage : public Filter {
public:
  /*
   * Create a moving average calculator with 0 as the default value
   *
   * @param buffer_size    The size of the buffer. The number of samples that constitute a valid reading
   */
  MovingAverage(int buffer_size);
  /*
   * Create a moving average calculator with a specified default value
   * @param buffer_size    The size of the buffer. The number of samples that constitute a valid reading
   * @param starting_value The value that the average will be before any data is added
   */
  MovingAverage(int buffer_size, double starting_value);
 
  /*
   * Add a reading to the buffer
   * Before:
   * [ 1 1 2 2 3 3] => 2
   *   ^
   * After:
   * [ 2 1 2 2 3 3] => 2.16
   *     ^
   * @param n  the sample that will be added to the moving average.
   */
  void add_entry(double n) override;

  double get_value() const override;

  int get_size() const;
 
private:
  int buffer_index;           // index of the next value to be overridden
  std::vector<double> buffer; // all current data readings we've taken
  double current_avg;         // the current value of the data
};

class ExponentialMovingAverage : public Filter {
public:
  /*
   * Create a moving average calculator with 0 as the default value
   *
   * @param buffer_size    The size of the buffer. The number of samples that constitute a valid reading
   */
  ExponentialMovingAverage(int buffer_size);
  /*
   * Create a moving average calculator with a specified default value
   * @param buffer_size    The size of the buffer. The number of samples that constitute a valid reading
   * @param starting_value The value that the average will be before any data is added
   */
  ExponentialMovingAverage(int buffer_size, double starting_value);
 
  /*
   * Add a reading to the buffer
   * Before:
   * [ 1 1 2 2 3 3] => 2
   *   ^
   * After:
   * [ 2 1 2 2 3 3] => 2.16
   *     ^
   * @param n  the sample that will be added to the moving average.
   */
  void add_entry(double n) override;

  double get_value() const override;

  int get_size();
 
private:
  int buffer_index;           // index of the next value to be overridden
  std::vector<double> buffer; // all current data readings we've taken
  double current_avg;         // the current value of the data
};