将司仪与高斯先验一起使用 [英] Using emcee with Gaussian Priors

问题描述

我尝试在使用司仪之前先使用高斯，似乎无法完全弄清楚.基本上我想替换

I'm trying to use a gaussian prior using emcee and can't seem to fully figure it out. Basically I want to replace

def lnprior(theta):
     a, b, c = theta
     if 1.0 < a < 2.0 and 1.0 < b < 2.0 and 1.0 < c < 2.0:
        return 0.0
     return -np.inf

具有将从具有mu和sigma的高斯分布中采样"a"的值.我该怎么做?这样吗?

with something that would sample 'a' from a gaussian distribution with a mu and sigma. How would I do that? Like this?

def lnprior(theta):
     a, b, c = theta
     if 1.0 < b < 2.0 and 1.0 < c < 2.0:
        return 0.0
     if 0<a<20:
         mu=10
         sigma=1
         s=np.random.normal(mu, sigma)
         return s
     return -np.inf

那似乎不太正确吗?

推荐答案

以下方法似乎对我有用

def lnprior(theta):
    a, b, c = theta
    #flat priors on b, c
    if not 1.0 < b < 2.0 and 1.0 < c < 2.0:
        return -np.inf
    #gaussian prior on a
    mu = 10
    sigma = 1
    return np.log(1.0/(np.sqrt(2*np.pi)*sigma))-0.5*(a-mu)**2/sigma**2

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