code: def averageSize(self):
          
          cm = self.centerOfMass()
          coords = self.coordinates(copy=False)
          if not len(coords):
              return 0
          s, c = 0.0, 0.0
          n = len(coords)
          step = int(n / 10000.0) + 1
          for i in np.arange(0, n, step):
              s += utils.mag(coords[i] - cm)
              c += 1
          return s / c
docs: Calculate the average size of a mesh.
          This is the mean of the vertex distances from the center of mass.