Running average

libraries/RunningAverage/RunningAverage.cpp

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+// 
+//    FILE: RunningAverage.cpp
+//  AUTHOR: Rob Tillaart
+// VERSION: 0.1.01
+// PURPOSE: RunningAverage library for Arduino
+//
+// The library does store the last N individual values, to 
+// calculate the running average. 
+//
+// HISTORY: 
+// 0.1.00 - 2011-01-30 initial version
+// 0.1.01 - 2011-02-28 fixed missing destructor in .h
+//
+// Released to the public domain
+//
+
+#include "RunningAverage.h"
+#include <stdlib.h>
+
+RunningAverage::RunningAverage(int n)
+{
+	_size = n;
+	_ar = (float*) malloc(_size * sizeof(float));
+	clr();
+}
+
+RunningAverage::~RunningAverage()
+{
+	free(_ar);
+}
+
+// resets all counters
+void RunningAverage::clr() 
+{ 
+	_cnt = 0;
+	_idx = 0;
+	_sum = 0.0;
+	for (int i=0; i< _size; i++) _ar[i] = 0.0;
+}
+
+// adds a new value to the data-set
+void RunningAverage::add(float f)
+{
+	_sum -= _ar[_idx];
+	_ar[_idx] = f;
+	_sum += _ar[_idx];
+	_idx = (_idx + 1) % _size;
+	if (_cnt < _size) _cnt++;
+}
+
+// returns the average of the data-set added sofar
+float RunningAverage::avg()
+{
+	return _sum / _cnt;
+}
+
+// END OF FILE

libraries/RunningAverage/RunningAverage.h

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+#ifndef RunningAverage_h
+#define RunningAverage_h
+// 
+//    FILE: RunningAverage.h
+//  AUTHOR: Rob dot Tillaart at gmail dot com
+// PURPOSE: RunningAverage library for Arduino
+// VERSION: 0.1.01
+//     URL: http://arduino.cc/playground/Main/RunningAverage
+// HISTORY: See RunningAverage.cpp
+//
+// Released to the public domain
+//
+
+class RunningAverage 
+{
+	public:
+	RunningAverage(void);
+	RunningAverage(int);
+	~RunningAverage();
+	void clr();
+	void add(float);
+	float avg();
+
+protected:
+	int _size;
+	int _cnt;
+	int _idx;
+	float _sum;
+	float * _ar;
+};
+
+#endif
+// END OF FILE

libraries/RunningAverage/examples/ra_hour/ra_hour.pde

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+#include "RunningAverage.h"
+
+RunningAverage raMinute(60);
+RunningAverage raHour(60);
+
+int samples = 0;
+
+void setup(void) 
+{
+  Serial.begin(115200);
+  Serial.println("Demo RunningAverage lib - average per minute & hour");
+  raHour.clr();
+  raMinute.clr();
+}
+
+void loop(void) 
+{
+  long rn = random(0, 100);
+  raMinute.add(rn);
+  samples++;
+  
+  if (samples % 60 == 0) raHour.add(raMinute.avg());
+  
+  Serial.print("  raMinute: ");
+  Serial.print(raMinute.avg(), 4);
+  Serial.print("  raHour: ");
+  Serial.println(raHour.avg(), 4);
+}

libraries/RunningAverage/examples/ra_test/ra_test.pde

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+#include "RunningAverage.h"
+
+RunningAverage myRA(10); // use default size
+int samples = 0;
+
+void setup(void) 
+{
+  Serial.begin(115200);
+  Serial.println("Demo RunningAverage lib");
+  myRA.clr(); // explicitly start clean
+}
+
+void loop(void) 
+{
+  long rn = random(0, 100);
+  myRA.add(rn/100.0);
+  samples++;
+  Serial.print("Running Average: ");
+  Serial.println(myRA.avg(), 4);
+  
+  if (samples == 300)
+  {
+    samples = 0;
+    myRA.clr();
+  }
+  delay(100);
+}