def averageSize(self):
        """Calculate the average size of a mesh.
        This is the mean of the vertex distances from the center of mass."""
        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
Calculate the average size of a mesh.
        This is the mean of the vertex distances from the center of mass.