`NA` limits in coords

[eliocamp]

Setting NA in limits of coords in a similar fashion to scales ends up in an error.

library(ggplot2)

ggplot(cars, aes(speed, dist)) +
   geom_point() +
   coord_cartesian(ylim = c(25, NA))  # emulating scale_y_continuous(limits = c(25, NA))
#> Error in if (zero_range(range)) zero_width else diff(range): missing value where TRUE/FALSE needed

Created on 2018-09-21 by the reprex package (v0.2.0).

I've tinker a bit and found that the error is in this line:

ggplot2/R/coord-cartesian-.r

Line 121 in 01155ba

range <- range(scale$transform(limits))

Adding this:
limits <- ifelse(is.na(limits), scale$get_limits(), limits)
solves the issue in this case.

library(ggplot2)

scale_range <- function(scale, limits = NULL, expand = TRUE) {
   expansion <- if (expand) ggplot2:::expand_default(scale) else c(0, 0)
   
   if (is.null(limits)) {
      scale$dimension(expansion)
   } else {
      limits <- ifelse(is.na(limits), scale$get_limits(), limits)
      range <- range(scale$transform(limits))
      scales::expand_range(range, expansion[1], expansion[2])
   } 
}

assignInNamespace("scale_range", scale_range, ns = "ggplot2")

ggplot(cars, aes(speed, dist)) +
   geom_point() +
   coord_cartesian(ylim = c(25, NA))  

Created on 2018-09-21 by the reprex package (v0.2.0).

I'm not versed enough on how ggplot2 handles coords to know if it's a robust fix across different coords, though.

[atusy]

There's another inconsistency among coord_cartesian() and scale_*_continuous1().
Limits for coord_cartesian can be length larger than 3 due to range() in scale_range() unlike limits for scale_*_continuous().

Thus, in ifelse(is.na(limits), scale$get_limits(), limits) by @eliocamp, scale$get_limits() will be re-cycled to have same length with limits.
It may result in unexpected behavior.

library(ggplot2)

scale_range <- function(scale, limits = NULL, expand = TRUE) {
   expansion <- if (expand) ggplot2:::expand_default(scale) else c(0, 0)
   
   if (is.null(limits)) {
      scale$dimension(expansion)
   } else {
      limits <- ifelse(is.na(limits), scale$get_limits(), limits)
      range <- range(scale$transform(limits))
      scales::expand_range(range, expansion[1], expansion[2])
   } 
}

assignInNamespace("scale_range", scale_range, ns = "ggplot2")

ggplot(cars, aes(speed, dist)) +
   geom_point() +
   coord_cartesian(ylim = c(25, NA, NA))

Created on 2018-11-23 by the reprex package (v0.2.1)

I think limits argument should only accept

- a finite value
- a numeric vector of length 2 with or without NA

Is there any reason that coord_cartesian needs to accept limits with length larger than 2?

[hadley]

I just tried to do this too!

[lock]

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