Rework of averageData (#41)

* new average algorithm

* fixed casting type

* attempting to get rid of casting

* fixed casting and added comments

src/utils/SensorDataUtils.cpp

@@ -88,13 +88,19 @@ namespace{
     int getAverageOfSensorDataIntField(const std::vector<SensorData>& datas, int (*selectorFct)(const SensorData&)){
         //TODO: we gotta be careful for int overflow here
 
-        int total = 0;
+        double i = 1;
+        double currentAvg = 0;
         for (const auto& sensorData: datas){
-            total += selectorFct(sensorData);
+            // Aaron's Algorithm for Average
+            // The average is a simplified version of A' =(A(n-1) + a)/n
+            //    where A' is the new average at n, A is the current average at n - 1, and a is the value at n
+            currentAvg *= 1 - (1.0 / i);
+            currentAvg += selectorFct(sensorData) / i;
+            i++;
         }
 
         // TODO: this cast is technically iffy, but once we switch to fixed size vectors we should be safe
-        return total / static_cast<int>(datas.size());
+        return static_cast<int>(currentAvg);
     }
 }