How to Create a GGPlot Stacked Bar Chart

Prerequisites

Load required packages and set the theme function theme_minimal() as the default theme:

library(dplyr)   # For data manipulation
library(ggplot2) # For data visualization
theme_set(theme_minimal())

Data preparation

Data derived from ToothGrowth data sets are used. ToothGrowth describes the effect of Vitamin C on tooth growth in Guinea pigs. Three dose levels of Vitamin C (0.5, 1, and 2 mg) with each of two delivery methods [orange juice (OJ) or ascorbic acid (VC)] are used :

df <- data.frame(
  supp = rep(c("VC", "OJ"), each = 3),
  dose = rep(c("D0.5", "D1", "D2"), 2),
  len = c(6.8, 15, 33, 4.2, 10, 29.5)
  )

head(df)

##   supp dose  len
## 1   VC D0.5  6.8
## 2   VC   D1 15.0
## 3   VC   D2 33.0
## 4   OJ D0.5  4.2
## 5   OJ   D1 10.0
## 6   OJ   D2 29.5

• len : Tooth length
• dose : Dose in milligrams (0.5, 1, 2)
• supp : Supplement type (VC or OJ)

Basic plots

p <- ggplot(df, aes(x = dose, y = len))+
  geom_col(aes(fill = supp), width = 0.7)
p

Add labels

4 steps required to compute the position of text labels:

• Group the data by the dose variable
• Sort the data by dose and supp columns. As stacked plot reverse the group order, supp column should be sorted in descending order.
• Calculate the cumulative sum of len for each dose category. Used as the y coordinates of labels. To put the label in the middle of the bars, we’ll use cumsum(len) - 0.5 * len.
• Create the bar graph and add labels

# Arrange/sort and compute cumulative summs
library(dplyr)
 df2 <- df %>%
  group_by(dose) %>%
  arrange(dose, desc(supp)) %>%
  mutate(lab_ypos = cumsum(len) - 0.5 * len) 
df2

## # A tibble: 6 x 4
## # Groups:   dose [3]
##   supp  dose    len lab_ypos
##   <fct> <fct> <dbl>    <dbl>
## 1 VC    D0.5    6.8      3.4
## 2 OJ    D0.5    4.2      8.9
## 3 VC    D1     15        7.5
## 4 OJ    D1     10       20  
## 5 VC    D2     33       16.5
## 6 OJ    D2     29.5     47.8

# Create stacked bar graphs with labels
p <- ggplot(data = df2, aes(x = dose, y = len)) +
  geom_col(aes(fill = supp), width = 0.7)+
  geom_text(aes(y = lab_ypos, label = len, group =supp), color = "white")
p

Customized bar plots

Use the function scale_fill_manual() to set manually the bars border line colors and area fill colors.

p + scale_fill_manual(values = c("#0073C2FF", "#EFC000FF"))