Custom formating of axis tick labels

[dazu89]

Apparently, ggplot2 relies on sf to draw the graticule and axes labels. Currently, when trying to plot to tikzDevice the usage of plotmath expression for the degree symbol in the axes labels paste0(abs(x), "*degree", dir[pos]) (see degreeLabelsEW function) leads to an error as ‹there is specifically no support for input of plotmath characters as unicode since the user can simply input Latex math directly› (Tikz User Manual). I wanted to suggest to hard code the degree symbol as \u00B0 which is rendered correctly with the default graphic device but also with tikzDevice using the options(tikzDefaultEngine = 'xetex').

> sessionInfo()
R version 4.4.0 (2024-04-24 ucrt)
Platform: x86_64-w64-mingw32/x64
Running under: Windows 10 x64 (build 19045)

Matrix products: default

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
[1] scales_1.3.0      tikzDevice_0.12.6 ggplot2_3.5.1     sf_1.0-16        

loaded via a namespace (and not attached):
 [1] vctrs_0.6.5        cli_3.6.2          rlang_1.1.3        DBI_1.2.2         
 [5] KernSmooth_2.23-22 png_0.1-8          generics_0.1.3     labeling_0.4.3    
 [9] glue_1.7.0         colorspace_2.1-0   e1071_1.7-14       fansi_1.0.6       
[13] grid_4.4.0         munsell_0.5.1      classInt_0.4-10    tibble_3.2.1      
[17] lifecycle_1.0.4    compiler_4.4.0     filehash_2.4-5     dplyr_1.1.4       
[21] Rcpp_1.0.12        pkgconfig_2.0.3    rstudioapi_0.16.0  digest_0.6.35     
[25] farver_2.1.1       R6_2.5.1           class_7.3-22       tidyselect_1.2.1  
[29] utf8_1.2.4         pillar_1.9.0       magrittr_2.0.3     tools_4.4.0       
[33] proxy_0.4-27       withr_3.0.0        gtable_0.3.5       units_0.8-5

[edzer]

I wanted to suggest to hard code the degree symbol as \u00B0 which is rendered correctly with the default graphic device but also with tikzDevice using the options(tikzDefaultEngine = 'xetex').

Interesting thought, but how do we make sure that this works across all graphic devices, given that graphics is not part of the package testing code? Maybe start with implementing your special case only?