Add dollar formatting to one plot in a facet wrap plot in ggplot-CodePudding

I am trying to add dollar formatting using the scales package scales::dollar_format() to a single plot (Sales) of a facet wrap plot

z <- data.frame(months = month.name, sales = runif(12, min = 3000000, max = 60000000), cases = round(runif(12, min = 100, max = 1000),0)) %>% pivot_longer(!months, names_to = "variable", values_to = "metric")

ggplot(data = z,
       aes(x = months, y = metric))  
  geom_bar(stat = 'identity')  
  facet_wrap(~ variable, ncol = 1, scales = "free_y")

I've tried using scale_y_continuous(labels = scales::dollar_format()) but it obviously adds it to both.

How can I add this to only the Sales plot and not the Cases plot?

CodePudding user response：

There is no elegant way to do this in vanilla ggplot2. In you particular case, because your two scales have very different ranges, you can hack a solution together by giving a function that conditionally formats the labels.

library(ggplot2)
library(tidyr)

z <- data.frame(months = month.name, sales = runif(12, min = 3000000, max = 60000000), cases = round(runif(12, min = 100, max = 1000),0)) %>%
  pivot_longer(!months, names_to = "variable", values_to = "metric")

p <- ggplot(data = z,
       aes(x = months, y = metric))  
  geom_bar(stat = 'identity')  
  facet_wrap(~ variable, ncol = 1, scales = "free_y")

p   scale_y_continuous(
  labels = ~ if (any(.x > 1e3)) scales::dollar(.x) else .x
)

If your case gets more complicated however, you could use ggh4x::facetted_pos_scales() to give a particular scale to a particular panel. (Disclaimer: I'm the author of ggh4x)

p   ggh4x::facetted_pos_scales(y = list(
  variable == "sales" ~ scale_y_continuous(labels = scales::dollar_format())
))

^{Created on 2022-03-09 by the reprex package (v2.0.1)}