如何使用R获得dnorm曲线

Question

x1000 <- rep(NA, 1000)
N = 10

for(i in 1:1000){
  x1000[i] <- mean(rpois(1000, 0.3))
}
hist(x1000, freq = F)

curve(dnorm(x1000, mean = 0.3, sd = sqrt(0.3)))

我试图获得重叠的曲线。但是，它给了我：

Error in curve(dnorm(x1000, mean = 0.3, sd = sqrt(0.3))) : 
  'expr' must be a function, or a call or an expression containing 'x'

Answer 1

你很接近，这就是你所要求的（技术上）：

hist(x1000, col="red", freq=F)
curve( dnorm(x, mean=.3,sd=sqrt(.3)), col="blue", add=T) # expression containing 'x'

但我认为你真正想要的是：

curve( dnorm(x, mean=mean(x1000),sd=sd(x1000)), col="blue", add=T)

或者：

curve( dnorm(x, mean=mean(x1000),sd=sqrt(mean(x1000)/length(x1000)), col="blue", add=T)