公式：

$\begin{aligned} &SmoothCtr = (\alpha +CurrentC -1)/(\alpha +\beta +CurrentI -2) \\ &mean = \alpha /(\alpha+\beta) \\ &mode = (\alpha -1) /(\alpha + \beta -2) \end{aligned}$

#self.alpha = mean*(mean*(1-mean)/(var+0.000001)-1)
self.alpha = (mean+0.000001) * ((mean+0.000001) * (1.000001 - mean) / (var+0.000001) - 1)
#self.beta = (1-mean)*(mean*(1-mean)/(var+0.000001)-1)
self.beta = (1.000001 - mean) * ((mean+0.000001) * (1.000001 - mean) / (var+0.000001) - 1)

参考：https://zhuanlan.zhihu.com/p/21724759

https://jiayi797.github.io/2017/07/09/%E8%BD%AC%E5%8C%96%E7%8E%87%E9%A2%84%E4%BC%B0%E4%B9%8B%E8%B4%9D%E5%8F%B6%E6%96%AF%E5%B9%B3%E6%BB%91/