Error when setting breaks in `coord_radial()`

[Yunuuuu]

library(ggplot2)
data <- reshape2::melt(matrix(rnorm(100), 10))
ggplot(data, aes(Var1, Var2)) +
    geom_tile(aes(fill = value)) +
    scale_fill_viridis_c() +
    scale_x_discrete(breaks = 1:2) +
    coord_radial()
#> Error in switch(params$position, top = , right = , theta.sec = -Inf, Inf): EXPR must be a length 1 vector

^{Created on 2025-01-07 with reprex v2.1.0}

I have using the development version of ggplot2.

Session info

sessioninfo::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#>  setting  value
#>  version  R version 4.4.2 (2024-10-31)
#>  os       Ubuntu 24.04.1 LTS
#>  system   x86_64, linux-gnu
#>  ui       X11
#>  language en
#>  collate  C.UTF-8
#>  ctype    C.UTF-8
#>  tz       Asia/Shanghai
#>  date     2025-01-07
#>  pandoc   3.1.3 @ /usr/bin/ (via rmarkdown)
#> 
#> ─ Packages ───────────────────────────────────────────────────────────────────
#>  package      * version    date (UTC) lib source
#>  cli            3.6.3      2024-06-21 [1] CRAN (R 4.4.0)
#>  digest         0.6.37     2024-08-19 [1] CRAN (R 4.4.2)
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#>  fs             1.6.5      2024-10-30 [1] CRAN (R 4.4.2)
#>  generics       0.1.3      2022-07-05 [1] CRAN (R 4.4.0)
#>  ggplot2      * 3.5.1.9000 2025-01-06 [1] Github (tidyverse/ggplot2@efc53cc)
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#>  reshape2       1.4.4      2020-04-09 [1] CRAN (R 4.4.0)
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#> 
#> ──────────────────────────────────────────────────────────────────────────────

[teunbrand]

While I agree that it shouldn't throw an error here, I'm having a hard time to grok the intention of this code. Even in Cartesian coordinates, the axis will not display labels.

[Yunuuuu]

Maybe something like this?

ggplot(data, aes(as.factor(Var1), Var2)) +
    geom_tile(aes(fill = value)) +
    scale_fill_viridis_c() +
    scale_x_discrete(breaks = 1:2)

It seems that scale_x_discrete() behaves differently with continuous variables. I initially thought that scale_x_discrete() would match the breaks with the unique values.

[teunbrand]

Discrete position scales generally just keep track of the range of continuous data but don't base their categorical limits or breaks on them. The scale cannot find any discrete values, so it begets empty limits, making the breaks = 1:2 obsolete as discrete breaks are required to be a subset of discrete limits.

[teunbrand]

Somewhat simplified reprex, note that also using empty breaks in the radial axis causes troubles.

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

p <- ggplot(mtcars, aes(mpg, disp)) +
  geom_point() +
  coord_radial()

p + scale_x_continuous(breaks = character())
#> Error in switch(params$position, top = , right = , theta.sec = -Inf, Inf): EXPR must be a length 1 vector

p + scale_y_continuous(breaks = character())
#> Error in `setup_params()` at ggplot2/R/ggproto.R:188:17:
#> ! `params$position` must be one of "top", "right", "bottom", or "left",
#>   not "theta".

^{Created on 2025-01-07 with reprex v2.1.1}

[Yunuuuu]

Thanks for the PR! I’ve tested it, and it works well with this example.

Another associated warning message with this example:

Warning message:
In groups$key$position : partial match of 'position' to 'positions'

This appears to correspond to the following line in the code:

ggplot2/R/guides-.R

Line 544 in efc53cc

position <- groups$key$position[i]

[teunbrand]

Another associated warning

Thanks, nice catch!

[Yunuuuu]

After using the development version of ggplot2 for the past few days, I encountered another warning message. Would this be something that can be fixed via this associated pull request, or should I open a new issue and make a commit?

library(ggplot2)
    ggplot(mtcars, aes(wt, mpg)) +
        geom_point(aes(colour = factor(cyl))) +
        theme(
            legend.position = "inside",
            legend.position.inside = c(0.5, 0.5)
        )
Warning messages:
1: In `*tmp*`$coord : partial match of 'coord' to 'coords'
2: In groups$key$position : partial match of 'position' to 'positions'

[teunbrand]

I've taken it along in de2648b