中文说明：此代码为选择良好的示例为阳性样本，为初学者，这非常只有所述的文件中，该区域定位的负样本是围绕中央的阳性样品的两个不同半径的环形区域 （R1 < R2）。负样本是随机选择在 thi
English Description：
this code for select good sample for positive sample,this very usefule for beginner, As described in the paper, the region to locate the negative samples is an annular region around the central positive samples with two different radii (R1