How to plot the confidence interval of times series in R?-CodePudding

I have some problems about drawing confidence interval for time series in R. The data is down below...

dat <- as.data.frame(cbind(time=c(1980:2019), value=rnorm(40)))
head(dat)
  time      value
1 1980 -1.7196037
2 1981 -0.8135920
3 1982 -0.7451891
4 1983  0.7011315
5 1984  0.5657109

I transformed the "value" become time series,

ts(dat$value, start=1980, end=2019)

but when I try to plot the confidence intervals, it doesn't work,

ggplot(dat, aes(x=time, y=value))   
  geom_line()   geom_hline(yintercept=0)   
  geom_ribbon(aes(ymin=mean(value)-sd(value), 
                  ymax=mean(value) sd(value)), alpha=0.05)

but it returned...

Can someone helps me, thanks.

CodePudding user response：

First of all, I'm not sure why you converted to ts as {ggplot2} can't use it and you didn't assign it back to dat in any case.

But the main issue is that you are calculating your ribbon off of all the data points so it's just one big rectangle.

If you have multiple y values at each x value, then you can use stat_summary() to calculate the mean and error as desired. See example below:

library(tidyverse)

d <- data.frame(x = rep(1:5, 5), y = runif(25))

d %>% 
  ggplot(aes(x, y))  
  geom_point()  
  geom_line(stat = "summary", size = 2)  
  stat_summary(fun = mean,
               fun.min = function(x) mean(x) - sd(x), 
               fun.max = function(x) mean(x)   sd(x), 
               geom = "ribbon", 
               alpha = 0.5)

^{Created on 2022-04-07 by the reprex package (v2.0.1)}