How do I plot the mean instead of the median with geom_boxplot?
Solution 1
There are a few ways to do this:
1. Using middle
The easiest is to simply call:
plot <- ggplot(data = df, aes(y = dust, x = wind)) +
geom_boxplot(aes(middle = mean(dust))
2. Using fatten = NULL
You can also take advantage of the fatten
parameter in geom_boxplot()
. This controls the thickness of the median line. If we set it to NULL
, then it will not plot a median line, and we can insert a line for the mean using stat_summary
.
plot <- ggplot(data = df, aes(y = dust, x = wind)) +
geom_boxplot(fatten = NULL) +
stat_summary(fun.y = mean, geom = "errorbar", aes(ymax = ..y.., ymin = ..y..),
width = 0.75, size = 1, linetype = "solid")
print(plot)
Output using fatten = NULL
As you can see, the above method plots just fine, but when you evaluate the code it will output some warning messages because fatten
is not really expected to take a NULL
value.
The upside is that this method is possibly a bit more flexible, as we are essentially "erasing" the median line and adding in whatever we want. For example, we could also choose to keep the median, and add the mean as a dashed line.
Solution 2
ggplot(df) +
geom_boxplot(
aes(
x = wind, ymin = min(dust), lower = quantile(dust, .25),
middle = mean(dust), upper = quantile(dust, .75),
ymax = max(dust)
), stat = "identity"
)
Admin
Updated on June 16, 2022Comments
-
Admin almost 2 years
for some inane reason, I need to create a boxplot where the middle line is the mean instead of the median. I checked stackoverflow already and found examples of adding a mean line, but not exactly what I need. I tried using stat_smooth but no dice. Any ideas?
code below:
dust <- c(4.5, 3.7, 5, 5.2, 8.5, 6.6, 4.7, 5, 5.7, 4.3, 2.3, 7.6, 5.2, 6, 8.7, 7.5, 7.7, 11, 9, 6.5, 8.7, 5, 2.2, 7.5, 7.5, 3.5) wind <- c("Present", "Absent", "Absent", "Absent", "Absent", "Absent", "Absent", "Absent", "Absent", "Present", "Absent", "Absent", "Present", "Present", "Absent", "Absent", "Absent", "Absent", "Absent", "Present", "Absent", "Present", "Absent", "Absent", "Absent", "Present") df <- data.frame(dust,wind) plot <- ggplot(data=df,aes(x=wind,y=dust))+geom_boxplot()+stat_smooth() plot
-
treetopdewdrop about 2 yearsThis answer is not correct. aes middle does not have the desired effect.
-
Marcus Campbell about 2 yearsAh, I just checked and it looks like you are right! It looks like this solution no longer works with current versions of ggplot2. I'll edit this post with a correct solution later today.