ggplot2 horizontal line for bar chart

August 31, 2023

I have following barchart drawn using ggplot2 in R. We would like to I would like to draw blue line for "Total" values. I tried using geom_linerange and geom_errorbar, but was not successful, how can I get the blue lines for hosrizantal bar chart?

dat=read.csv(textConnection(
  "Category,Value1,Value2,Total,Group
A,10,10,20,1
B,20,30,50,1
C,5,2,7,1
D,5,10,15,2
E,10,20,30,2
F,30,4,34,2"))

library(tidyverse)
library(ggplot2)

dat %>%
  arrange(desc(Group), Total) %>%
  mutate(Category = fct_inorder(Category)) %>%
  pivot_longer(Value1:Total) -> dat2

ggplot(filter(dat2, !name %in% c("Value2","Total")),
       aes(value, Category, label = value)) +
  geom_col(aes(fill = name), position = position_stack(reverse = TRUE)) +
  geom_text(position = position_stack(vjust = 0.5, reverse = TRUE))  +
  geom_text(data = filter(dat2, name == "Total"),
            hjust = -0.5

)

>Solution :

You can achieve your desired result using a geom_segment where for the y and yend aes you have to convert Category to a numeric and shift by +/- the half bar width which by default is .9 / 2 = .45:

library(ggplot2)

ggplot(
  dplyr::filter(dat2, !name %in% c("Value2", "Total")),
  aes(value, Category, label = value)
) +
  geom_col(aes(fill = name), position = position_stack(reverse = TRUE)) +
  geom_segment(
    data = filter(dat2, name == "Total"),
    aes(
      xend = value,
      y = as.numeric(factor(Category)) - .45,
      yend = as.numeric(factor(Category)) + .45
    ),
    color = "blue"
  ) +
  geom_text(position = position_stack(vjust = 0.5, reverse = TRUE)) +
  geom_text(
    data = filter(dat2, name == "Total"),
    hjust = -0.5
  )