ggplot2: creating double bar plot with one column representing x and y

Question

I want to create a double-bar plot from a dataset similar to the following data:

df <- data.frame(
      month=c("2","3","11","3","4","1","5","3","12","11","10","9","9","7","5","3","2","5","12","10"),
      member_casual=c("member","casual","member","casual","member","casual","casual","casual","member","casual",
                      "member","casual","member","casual","member","casual","member","member","member","casual")
    )

I want the x to be the month column, and the y to be the count of each month's values. I need double bars to represent member and casual.

I've done something similar to the following code but I couldn't calculate the count of each month.

ggplot(df, aes(x=x, y=y))+
  geom_bar(stat = "identity", position = 'dodge')+
  scale_x_continuous(breaks = 1:12)+
  theme_classic()

This is an example of what it should look like Double bar example

I'm new to R and ggplot2 I hope that someone can help me.

Answer 1

You can get your desired result by using stat="count" (which is the default for geom_bar) which requires to drop y = y. Additionally, to get a grouped bar chart you have to add your groups by mapping the grouping variable on fill:

df <- data.frame(
  month = c("2", "3", "11", "3", "4", "1", "5", "3", "12", "11", "10", "9", "9", "7", "5", "3", "2", "5", "12", "10"),
  member_casual = c(
    "member", "casual", "member", "casual", "member", "casual", "casual", "casual", "member", "casual",
    "member", "casual", "member", "casual", "member", "casual", "member", "member", "member", "casual"
  )
)

library(ggplot2)

ggplot(df, aes(as.numeric(month), fill = member_casual)) +
  geom_bar(position = position_dodge(preserve = "single")) +
  scale_x_continuous(breaks = 1:12) +
  theme_classic()