code: def segment_tripoints(self, ratio=0.33333):
          
  
          segments = self.identify_segments()
          points = self.points
  
          mids1 = ratio*points[segments[:,0]] + (1.0-ratio)*points[segments[:,1]]
          mids2 = (1.0-ratio)*points[segments[:,0]] + ratio*points[segments[:,1]]
  
          mids = np.vstack((mids1,mids2))
          mid_xpt, mid_ypt = mids[:,0], mids[:,1]
  
          return mid_xpt, mid_ypt
docs: Identify the trisection points of every line segment in the triangulation