r - Force ggplot2 scatter plot to be square shaped

Question

I can force ggplot2 scatter plot to be square shaped with the same x and y scaling using xlim() and ylim(), but it needs manual calculation of the limits. Is there any more convenient way of doing it?

By square shape I mean two requirements:

1. The same scale on x and y axis.
2. The equal length of x and y axis.

Answer 1

If you want to make the distance scale points the same, then use coord_fixed():

p <- ggplot(...)
p <- p + coord_fixed() # ratio parameter defaults to 1 i.e. y / x = 1

If you want to ensure that the resulting plot is square then you would also need to specify the x and y limits to be the same (or at least have the same range). xlim and ylim are both arguments to coord_fixed. So you could do this manually using those arguments. Or you could use a function to extract out limits from the data.