Change order of segments in stacked barplot - r

Question

How can I change the order of the segments in the following stacked barplot
from -- (left) to ++ (right) and NA on the right?
library(dplyr)
library(ggplot2)
library(tidyr)
size <- 100
df <- data.frame(item1 = sample(c(1:5, 1:5, 99), size = size, replace = TRUE),
item2 = sample(c(1:5, 1:4, 99), size = size, replace = TRUE),
item3 = sample(c(1:5, 1:3, 99), size = size, replace = TRUE),
item4 = sample(c(1:5, 1:5, 99), size = size, replace = TRUE),
item5 = sample(c(1:5, 1:4, 99), size = size, replace = TRUE))
# Stacked barplot
df %>% pivot_longer(cols = starts_with("item")) %>%
group_by(name) %>%
count(value) %>%
mutate(perc = 100 / sum(n) * n) %>%
ungroup() %>%
mutate(value = factor(value, levels = c(1:5, 99), labels = c("--", "-", "0", "+", "++", "NA"))) %>%
ggplot(aes(x = name, y = perc, fill = value)) + geom_col() +
coord_flip()
Created on 2022-12-12 with reprex v2.0.2

Answer 1

You can reverse the order of the stack by using position_stack(reverse = TRUE):
set.seed(123)
library(tidyr)
library(ggplot2)
library(dplyr)
df %>% pivot_longer(cols = starts_with("item")) %>%
group_by(name) %>%
count(value) %>%
mutate(perc = 100 / sum(n) * n) %>%
ungroup() %>%
mutate(value = factor(value, levels = c(1:5, 99), labels = c("--", "-", "0", "+", "++", "NA"))) %>%
ggplot(aes(x = name, y = perc, fill = value)) +
geom_col(position = position_stack(reverse = TRUE)) +
coord_flip()