ggplot2 removes zero when using scale_x_sqrt

Question

When I plot data whose x coordinate starts with zero using ggplot2 and I use the scale_x_sqrt option, the plot starts from 1 on the x-axis instead of zero. If I add limits=c(-0.1, 100) I get an error that "NaNs produced". How can I get ggplot2 to include zero?

Answer 1

You can have the axis go down to zero with a square root transformation, but not below zero. The transformation produces imaginary values for x-values below zero.

library(tidyverse)

ggplot(mtcars, aes(wt, mpg)) +
  geom_point() +
  scale_x_sqrt(limits=c(0,6), breaks=0:6, expand=c(0,0))

Answer 2

See: https://github.com/tidyverse/ggplot2/issues/980

The workaround they describe is:

library(ggplot2)
library(scales)
mysqrt_trans <- function() {
    trans_new("mysqrt", 
              transform = base::sqrt,
              inverse = function(x) ifelse(x<0, 0, x^2),
              domain = c(0, Inf))
}

ggplot(mtcars, aes(wt, mpg)) + geom_point() +
  scale_x_continuous(trans="mysqrt", limits=c(0, NA))

In contrast to the other answers poster here this allows for some space to the left of zero.