Support for using `I()` to use NPC corodinates seems incomplete

[aphalo]

@teunbrand I could not find an open issue on this, but I remember seeing a rather recent commit by you implementing this new feature. In 3.4.4.9000 I see it working in annotate() and in aes() but not with values mapped to constants in calls to geoms (at least geom_label()). By the way, it is great to see this implemented in 'ggplot2'. It makes several geometries in 'ggpp' redundant which is, I think, an indication of usefulness, as now all geometries become usable with NPC coordinates.

library(ggplot2)

ggplot(data = mtcars,
       mapping = aes(x = disp, y = mpg, colour = factor(cyl))) +
  geom_point() +
  annotate(geom = "label", x = I(0.5), y = I(0.9), label = "a label")

ggplot() +
  geom_point(mapping = aes(x = disp, y = mpg, colour = factor(cyl)),
             data = mtcars) +
  geom_label(mapping = aes(x = I(x), y = I(y), label = label),
             data = data.frame(x = 0.5, y = 0.9, label = "a label"))

ggplot(data = mtcars,
       mapping = aes(x = disp, y = mpg, colour = factor(cyl))) +
  geom_point() +
  geom_label(x = I(0.5), y = I(0.9), label = "a label", colour = "black")

ggplot(data = mtcars,
       mapping = aes(x = disp, y = mpg, colour = factor(cyl))) +
  geom_point() +
  geom_label(x = 300, y = 32, label = "a label", colour = "black")

^{Created on 2024-01-22 with reprex v2.1.0}

[teunbrand]

Thanks for the report @aphalo! I'm glad it come before the release rather than afterwards. I agree with you about the usefulness of non-data coordinates.
The culprit of this behaviour seems to be here:

ggplot2/R/geom-.R

Line 179 in a4be39d

data[aes_params] <- params[aes_params]

Where the AsIs class seem to be dropped. You can replicate that behaviour like this. Note that the foo column is not an AsIs column anymore.

df <- mtcars
df["foo"] <- list(foo = I(10))
class(df$foo)
#> [1] "numeric"

^{Created on 2024-01-22 with reprex v2.1.0}

One possible way to remediate this, would be to convert to a list, do the assignment, and restore to data.frame again.

df <- unclass(mtcars)
df["foo"] <- list(foo = I(10))
df <- vctrs::data_frame(!!!df)
class(df$foo)
#> [1] "AsIs"

^{Created on 2024-01-22 with reprex v2.1.0}

[teunbrand]

Considered fixed in the RC by #5657