ggplot2 legend for stat_summary

Question

How can I create a legend informing that the red cross is the mean?

ggplot(results, aes(x=factor, y=proportionPositive)) +
geom_boxplot() +
stat_summary(fun.data = "mean_cl_normal", colour = "red", shape=4)

enter image description here

score 28 · Accepted Answer · answered Mar 03 '11 at 10:51

Here is one way of doing it:

Map an aesthetic to a shape, i.e. aes(shape="mean")
Create a manual shape scale, i.e. scale_shape_manual()

# Create dummy data
results <- data.frame(
  factor=factor(rep(1:10, 100)), 
  proportionPositive=rnorm(1000))

# Plot results
ggplot(results, aes(x=factor, y=proportionPositive)) +
      geom_boxplot() +
      stat_summary(fun.data = "mean_cl_normal", 
              aes(shape="mean"), 
              colour = "red",
              geom="point") +
      scale_shape_manual("", values=c("mean"="x"))

enter image description here

If you want to use pch symbolsl it's possible to use Unicode numbers. In order to do that, just replace the 'x' by an Unicode value: "\U" then Unicode value (e.g. `"\U22C4"`). See [Unicode table][1] [1]: http://www.fileformat.info/info/unicode/char/22c4/index.htm — Fábio, Dec 06 '16 at 16:26

score 1 · Answer 2 · edited Nov 10 '21 at 17:32

1

for me option "show.legend=TRUE" simply did work out:

ggplot(aes(x=stimulus, y=EPN, fill=strategy))+ 
  stat_summary(fun.data=mean_se, show.legend=TRUE, geom="bar", position="dodge", colour="black", linetype="solid", size=0.3)

edited Nov 10 '21 at 17:32

tjebo

21,977
7
58
94

answered Nov 10 '21 at 13:38

asenga

21
2

This surprisingly works, but not without adding a scale call, e.g., as above `... + scale_shape_manual(values=c("mean"="x"))` – tjebo Nov 10 '21 at 17:32

score 0 · Answer 3 · answered Oct 28 '17 at 18:21

To make it appear like a default legend (borrowing from @Andrie code):

ggplot(results, aes(x=factor, y=proportionPositive)) +
      geom_boxplot() +
      stat_summary(fun.data = "mean_cl_normal", 
              aes(shape=""), # Leave empty
              colour = "red",
              geom="point") +
      scale_shape_manual("mean", values= "") # Will show mean on top of the line

ggplot2 legend for stat_summary

3 Answers3

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