How to set just one limit for axes in ggplot2 with facets?

Question

This question is similar to this one: How to set limits for axes in ggplot2 R plots? , with the difference that I want to limit one side only (eg plot only for x>0 instead of -5000 < x < 5000 ) and do it with facets .

Note, I'd like to know solutions for both of these simple cases:

1. scale_x_continuous(limits = c(-5000, 5000)) ( the same as xlim(-5000, 5000) ) - it removes points entirely from consideration (eg they will not be used for geom_smooth())

2. coord_cartesian(xlim = c(-5000, 5000)) functions - it simply does not plot them (but still uses for geom_smooth())

This situation happens often when you use facet_wrap(~veg, scales = "free_x) and don't know what the upper x limit for each facet, but you know that they are always positive.

Answer 1

Set limits one-sided with NA. Works both in coord_ and scale_ functions

I generally prefer coord_ because it does not remove data. For the example below you would additionally need to remove the margin at 0, eg with expand.

library(ggplot2)    

carrots <- data.frame(length = rnorm(500000, 10000, 10000))
cukes <- data.frame(length = rnorm(50000, 10000, 20000))
carrots$veg <- 'carrot'
cukes$veg <- 'cuke'
vegLengths <- rbind(carrots, cukes)

ggplot(vegLengths, aes(length, fill = veg)) +
  geom_density(alpha = 0.2) +
  scale_x_continuous(limits = c(0, NA))
#> Warning: Removed 94542 rows containing non-finite values (stat_density).

ggplot(vegLengths, aes(length, fill = veg)) +
  geom_density(alpha = 0.2) +
  coord_cartesian(xlim = c(0, NA))

^{Created on 2020-04-30 by the reprex package (v0.3.0)}

remove the margin with expand. Also one sided possible. the right margin is set to the default mult expansion of 0.05 for continous axis.

ggplot(vegLengths, aes(length, fill = veg)) +
  geom_density(alpha = 0.2) +
  scale_x_continuous(expand = expansion(mult = c(0, 0.05))) +
  coord_cartesian(xlim = c(0, NA))

Answer 2

You can try

scale_x_continuous(limits = c(0, max(x)))

This will set the lower limit to zero, and the upper limit to the maximum of your data. Is that what you're looking for?