ggplot2_ combining line and barplot in one graph

Question

Let's say I'm creating the grouped barplot by something like this:

data <- data.frame(time = factor(1:3), type = LETTERS[1:4], values = runif(24)*10)
ggplot(data, aes(x = type, y = values, fill = time)) +
  stat_summary(fun=mean, geom='bar', width=0.55, size = 1, position=position_dodge(0.75))

Inside each type I want to connect all bar tops (meaning to connect 3 bars for A, 3 bars for B, and so on) with the line. I'd like to get something like that as a result:

Is there a way to do that ? Thank you!

Answer 1

I changed the code to another logic that I prefer, that is to prepare the data before using ggplot().

Code

library(dplyr)
library(ggplot2)

data <- data.frame(time = factor(1:3), type = LETTERS[1:4], values = runif(24)*10)

pdata <- data %>% group_by(type,time) %>% summarise(values = mean(values,na.rm = TRUE)) %>% ungroup()

pdata %>% 
  ggplot(aes(x = type, y = values)) +
  geom_col(
    mapping = aes(fill = time, group = time),
    width = 0.55,
    size = 1,
    position = position_dodge(0.75)
  )+
  geom_line(
    mapping = aes(group = type),
    size = 1,
    position = position_dodge2(.75)
  )

Output