字面解释：（自已的理解）局部加权回归散点平滑法lowess(locally weighted scatterplot smoothing),也是loess。--->局部加权回归散点平滑算法。rlowess:稳健局部加权加归。r---->robust.--->和参数权重相关。稳健局部加权回归（robust locally weighted regressio