某个平面内的一系列点的密度分布，通过求出x和y方向的点的概率，最后用矩形框画出密度大的区域。4000个数据，详解，效果不错，直接能运行。-The density distribution of a series of points in the plane, determined by the probability of the point x and y directions, the final draw-density region with a large rectangular box. 4000 data, explain, good results can be directly run.