Is there an option to set "," as default decimal point for axis labels in ggplot?

Question

When making a graph, ggplot2 has a lot of sensible defaults for scales that require extra work when trying to achieve the same result using scales.

An example:

library("ggplot2")
ggplot(mtcars, aes(drat, mpg)) + geom_point()

Note that this plot has one digit behind the decimal mark.

However, I live in the Netherlands and we're used to using a comma as decimal mark. This is easily done within scale_x_continuous:

ggplot(mtcars, aes(drat, mpg)) + 
  geom_point() + 
  scale_x_continuous(labels = scales::label_number(big.mark = ".", decimal.mark = ","))

What bugs me about this solution is that this also increases the number of digits: there's an extra, rather unnecessary, 0 at the end of each label. Of course, this can also be solved within scales::label_number(), by setting accuracy = 0.1 but that requires iteration (plotting and re-plotting to set the more sensible number of digits).

Is there an option to fix the default decimal mark used by ggplot? I'm looking for a solution where

ggplot(mtcars, aes(drat, mpg)) + 
  geom_point()

returns the same plot as

ggplot(mtcars, aes(drat, mpg)) + 
  geom_point() + 
  scale_x_continuous(labels = scales::label_number(
    big.mark = ".", 
    decimal.mark = ",",
    accuracy = 0.1
  ))

Answer 1

The key seems to be that format (from base R) and scales::number use different rules. We can revert to using format ...

myf <- function(x, ...) format(x, big.mark = ".", decimal.mark = ",", ...)
ggplot(mtcars, aes(drat, mpg)) +
  geom_point() +
  scale_x_continuous(labels = myf)

If you want to make these labels the global default I think you can do this:

scale_x_continuous <- function(..., labels = myf) {
  do.call(ggplot2::scale_x_continuous, c(list(...), labels = labels))
}