如何使用R得到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))) 

我想要得到叠加曲线。然而，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

你接近，这是你自找的（技术）是什么：

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

但我觉得你真的想要的是：

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)