rsquare.pde

PVector[] vectors = {leftHand, rightHand, leftElbow, rightElbow, leftShoulder, rightShoulder};

// returns m and b as 0 and 1 of an array respectively.
float[] fits = bestFit(vectors);

// this value is floating all over the place
float r2 = rsquare(vectors, fits[0], fits[1]);




float rsquare(PVector[] list, float m, float b) {
  float average = 0.0;
 
  for (PVector vector : list) {
    average += vector.y;
  }
  
  average = average / (float)list.length; 
  
  float sumtot = 0;
  float sumerr = 0;
  float sumreg = 0;
  
  for (PVector vector : list) {
    sumtot += pow(vector.y - average, 2);
    sumerr += pow(vector.y - vector.x * m + b, 2);
    sumreg += pow(vector.x * m + b - average, 2);
  }
  
  return 1 - sumerr / sumtot;
}

// Take a list of PVectors and calculate the slope and y-intercept
float[] bestFit(PVector[] list) {
  float n = (float)list.length;
  float m = 0;
  float b = 0;
  float sumproduct = 0;
  float sumx = 0;
  float sumx2 = 0;
  float sumy = 0;
  
  for (PVector v : list) {
    sumx += v.x;
    sumx2 += pow(v.x,2);
    sumy += v.y;
    sumproduct += v.x * v.y;
  }
  
  m = (sumproduct - (sumx * sumy / n)) / (sumx2 - pow(sumx,2)/n);
 
  b = sumy / n - m * sumx / n;
  
  float[] response = {m, b};
  return response;
}

Hello