向直方图添加拟合函数

Question

library(ggplot2)
library(fitdistrplus)
set.seed(1)
dat <- data.frame(n = rlnorm(1000))

# binwidth 
bw = 0.2

# fit a lognormal distribution
fit_params <- fitdistr(dat$n,"lognormal")

ggplot(dat, aes(n))  + 
  geom_histogram(aes(y = ..density..), binwidth = bw, colour = "black") + 
  stat_function(fun = dlnorm, size = 1, color = 'gray',
                args = list(mean = fit_params$estimate[1], sd = fit_params$estimate[2]))

# my defined function
myfun <- function(x, a, b) 1/(sqrt(2*pi*b(x-1)))*exp(-0.5*((log(x-a)/b)^2)) # a and b are meanlog and sdlog resp.

我想将myfun 定义的修改对数正态拟合到密度直方图。如何添加此功能？

Answer 1

也许你正在寻找这个。由于您的myfun 的域，某些值无法显示：

library(ggplot2)
library(fitdistrplus)
set.seed(1)
dat <- data.frame(n = rlnorm(1000))

# binwidth 
bw = 0.2

# fit a lognormal distribution
fit_params <- fitdistr(dat$n,"lognormal")
# my defined function
myfun <- function(x, a, b) 1/(sqrt(2*pi*b*(x-1)))*exp(-0.5*((log(x-a)/b)^2)) 
# a and b are meanlog and sdlog resp.

#Plot
ggplot(dat, aes(n))  + 
  geom_histogram(aes(y = ..density..), binwidth = bw, colour = "black") + 
  stat_function(fun = myfun, size = 1, color = 'gray',
                args = list(a = fit_params$estimate[1], b = fit_params$estimate[2]))

输出：