How to reorder bar charts with ggplot2

Problem

We'd like to reorder the bars of a bar chart. In our example below, the bars are not plotted in ascending or descending order.

library(tidyverse)
ggplot(df, aes(x = Position)) + geom_bar()

Data frame

df <- structure(list(Position = structure(c(3L, 3L, 1L, 1L, 1L, 2L), .Label = c("Defense", 
"Striker", "Zoalkeeper"), class = "factor"), Name = structure(c(2L, 
1L, 3L, 5L, 4L, 6L), .Label = c("Frank", "James", "Jean", "John", 
"Steve", "Tim"), class = "factor")), class = "data.frame", row.names = c(NA, 
-6L))

    Position  Name
1 Zoalkeeper James
2 Zoalkeeper Frank
3    Defense  Jean
4    Defense Steve
5    Defense  John
6    Striker   Tim

Solution

An alternative is using reorder to order the levels of a factor. In ascending (n) or descending order (-n) based on the count:

• Descending order

df %>%
  count(Position) %>%
  ggplot(aes(x = reorder(Position, -n), y = n)) +
  geom_bar(stat = 'identity') +
  xlab("Position")


• Ascending order

df %>%
  count(Position) %>%
  ggplot(aes(x = reorder(Position, n), y = n)) +
  geom_bar(stat = 'identity') +
  xlab("Position")

References

• stackoverflow