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rggplot2geom-bar
D. Studer
D. Studer

Reputation: 1875

ggplot: plot mean values instead of counts

I have the following sample data, which describe how long (duration) each respondent in my questionnaire needed to answer each question (question) and in which week the question was answered (there were several waves of the same questionnaire)

n <- 100

data2 <- data.frame(
  question = paste("q", sample(1:3, n, replace = TRUE), sep=""),
  week = sample(1:3, n, replace = TRUE),
  duration = round(rnorm(n, mean = 15, sd = 5), 0)
)

ggplot(aes(x = week, fill=question), data = data2) + geom_bar(position='stack') +
xlab("Week")

But how can I make the same plot with mean durations instead of counts (on the y-axis)?

Upvotes: 3

Views: 2314

Answers (2)

Andy Baxter
Andy Baxter

Reputation: 7626

stat_summary is the usual function for doing the calculations for you:

  ggplot(aes(x = week, y = duration, fill=question), data = data2) +
    stat_summary(fun=mean, geom="bar", position = "stack") +
    xlab("Week")

cols from stat_summary

Edit: This changed my practice the other week when I found out what stat_ layers can do! Demystifying stat_ layers in ggplot2

Upvotes: 2

Magnus Nordmo
Magnus Nordmo

Reputation: 951

I would use dplyr::group_bylike so.

data2 %>% 
  group_by(week,question) %>% 
  summarise(mean = mean(duration)) %>% 
  ggplot(aes(week,mean,fill = factor(question))) +
  geom_col()

Good luck!

Upvotes: 1

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