Question

我正在R中编写一个函数：

MH <- function(Nsim,var,initial) {
Total <- 0
X=rep(runif(1),Nsim)
X[1]=initial                                                          
for (i in 2:Nsim){
  Y=X[i-1]+rnorm(1, mean=0, sd=sqrt(var))
  alpha= fx(Y)/fx(X[i-1])
  u <- runif(1)
  X[i]=X[i-1]+(Y-X[i-1])*(u<alpha)
  Total=Total+as.numeric(u<alpha)
  }
  accept=Total/Nsim
  accept
}

我希望我的函数输出为'accept'，同时将矢量X直接保存到工作区中而不显示它，这样我以后可以用X做事。我知道这是一个基本问题，但有人可以帮我解决这个问题吗？

Answer 1

这样的事情

MH <- function(Nsim,var,initial) {
Total <- 0
X=rep(runif(1),Nsim)
X[1]=initial                                                          
for (i in 2:Nsim){
  Y=X[i-1]+rnorm(1, mean=0, sd=sqrt(var))
  alpha= fx(Y)/fx(X[i-1])
  u <- runif(1)
  X[i]=X[i-1]+(Y-X[i-1])*(u<alpha)
  Total=Total+as.numeric(u<alpha)
  }
  accept=Total/Nsim

  # put output into a list and give it class MH
  output <- list(accept = accept, X = X)
  class(output) <- "MH"
  output
}

# Write a custom print function for objects of
# class "MH"
print.MH <- function(x, ...){
  print(x[["accept"]])
}

out <- MH(10, 1, 1)
out # only prints the acceptance rate
out$accept # but can access accept
out$X # and X individually

如何将R中的函数输出直接保存到工作负载中而不显示它？

1 个答案: