Is there any package or function in R can calculate the coordinates of gravity centre for a 2-D arbitrary shape?? Suppose the x and y coordinates of my shape is x y 1 -12 30.4 45 2 Thanks! _________________________________________________________________ Windows Live Custom Domain£¬ÄúµÄÃâ·Ñµç×ÓÓʾ֡£ [[alternative HTML version deleted]]