Static expressions

[teunbrand]

This problem was identified in #6287 and affects 8 packages.

Generally, ggplot2 does not accept expressions as aesthetics.

library(ggplot2)

df <- data.frame(x = 1:2, y = 2:3)

ggplot(df, aes(x, y)) +
  geom_text(aes(label = expression(foo, bar)))
#> Don't know how to automatically pick scale for object of type <expression>.
#> Defaulting to continuous.
#> Error in `geom_text()`:
#> ! Problem while computing aesthetics.
#> ℹ Error occurred in the 1st layer.
#> Caused by error in `compute_aesthetics()`:
#> ! Aesthetics are not valid data columns.
#> ✖ The following aesthetics are invalid:
#> ✖ `label = expression(foo, bar)`
#> ℹ Did you mistype the name of a data column or forget to add `after_stat()`?

However, with the current CRAN ggplot2, you can circumvent this limitation by passing the label outside the mapping.

ggplot(df, aes(x, y)) +
  geom_text(label = expression(foo, bar))
#> Warning in is.na(x): is.na() applied to non-(list or vector) of type
#> 'expression'

In the dev version, we also reject expressions outside the mapping.

devtools::load_all("~/packages/ggplot2/")
#> ℹ Loading ggplot2

ggplot(df, aes(x, y)) +
  geom_text(label = expression(foo, bar))
#> Error in `geom_text()`:
#> ! Problem while setting up geom aesthetics.
#> ℹ Error occurred in the 1st layer.
#> Caused by error in `list_sizes()` at ggplot2/R/geom-.R:273:3:
#> ! `x$label` must be a vector, not an expression vector.

^{Created on 2025-01-22 with reprex v2.1.1}

Our increased strictness becomes a problem for reverse dependencies. I'm unsure wether ggplot2 should accommodate or the dependencies should follow ggplot2's conventions.

[teunbrand]

We shouldn't change the vctrs behaviour, but we should probably send out PRs/issues to packages.

[teunbrand]

Of the 8 packages mentioned:

• 3 did not actually have the described problem, they just threw a similar error. The problem was mostly using default_aes fields. They've been sent PRs.
• 3 packages did have this problem. They've been sent PRs.
• 2 packages are not on GitHub and their authors have been emailed.

This concludes what we can do about this problem from ggplot2's viewport, so I'm going to close this issue.