J Miller - 2 months ago 22

R Question

Is there a way to create a boxplot in R that will display with the box (somewhere) an "N=(sample size)"? The varwidth logical adjusts the width of the box on the basis of sample size, but that doesn't allow comparisons between different plots.

FWIW, I am using the boxplot command in the following fashion, where 'f1' is a factor:

`boxplot(xvar ~ f1, data=frame, xlab="input values", horizontal=TRUE)`

Answer

Here's some ggplot2 code. It's going to display the sample size at the sample mean, making the label multifunctional!

First, a simple function for `fun.data`

```
give.n <- function(x){
return(c(y = mean(x), label = length(x)))
}
```

Now, to demonstrate with the diamonds data

```
ggplot(diamonds, aes(cut, price)) +
geom_boxplot() +
stat_summary(fun.data = give.n, geom = "text")
```

You may have to play with the text size to make it look good, but now you have a label for the sample size which also gives a sense of the skew.