概率图模型 基于R语言 这本书中的第一个R语言程序

概率图模型 基于R语言 这本书中的第一个R语言程序

prior <- c(working =0.99,broken =0.01)
likelihood <- rbind(working = c(good=0.99,bad=0.01),broken =c(good=0.6,bad=0.4))
data <- c("bad","bad","bad","bad")

bayes <- function(prior, likelihood, data)
{
    posterior <- matrix(0, nrow=length(data), ncol=length(prior))
    dimnames(posterior) <- list(data, names(prior))

    initial_prior = prior
    for(i in 1:length(data))
    {
        posterior[i, ] <- 
            prior*likelihood[ , data[i]]/
            sum(prior * likelihood[ , data[i]])

        prior <- posterior[i , ]
    }

    return(rbind(initial_prior,posterior))
}


bayes(prior,likelihood,data)
matplot(bayes(prior,likelihood,data),t='b',lty =1,pch =20,col =c(3,2))

运行效果