`ggsave()` will fail to produce a file if the path contains diacritics

[mlaparie]

I got the exact same issue as in #4550, but it's been closed and I cannot comment in it. This was with Linux with R 4.4.2 and my libraries up to date.

When using a minimal reproducible environment based on Guix, with just the R package and necessary R libraries, using Rscript script.R or R --vanilla -e 'source("script.R")' would run the script and even create directories where necessary (so no permission issues), but ggsave() would produce the following warning (I think it should be an error, since it didn't create a file):

In grDevices::dev.off() : agg could not write to the given file

The error was not informative as to the actual cause, but I finally narrowed it down to one culprit: the absolute path of my working directory contained an acute diacritic. Somehow this did not prevent R from running and creating folders using ggsave(…, dir.create = TRUE), but the creation of the actual plot files was failing. It got resolved as soon as I removed the acute from the file hierarchy.

I am not sure if this is a ggsave() issue or a Guix issue. I imagine both are possible: on the one hand, it might be a Guix bug related to locales missing in the Guix container I created, and running the script from my env instead of the container would fix that. On the other hand, it could also be that ggsave() is unable to write files to paths containing diacritics even if R did not throw locale-related errors in the same condition.

If it's of any use, the data, scripts and Guix container to test which could be the cause are here: https://forgemia.inra.fr/mathieu.laparie/agrilusflight. If you think it's Guix, I'm happy to report this same issue to them.

[teunbrand]

Thanks for the report! Does the problem persist when rendering pure grid code?
For example:

ragg::agg_png("test.png") # adjust path to match problem
grid::grid.points(default.units = "npc")
dev.off()

If not, do you have the exact glyph/character/unicode that appears to be causing the issue?

[mlaparie]

Yes, it does:

mat@p3-guix ~/path/to/ÉLSbak/Vol/PCJ_agrilus_flight [env]$ Rscript test.R 
null device 
          1 
Warning message:
In dev.off() : agg could not write to the given file

The character in question here is É. I have not tried others.

[teunbrand]

Thanks for checking! Unfortunately it doesn't seem I can reproduce the issue just by including É in the filename on my Windows machine.
The persistence of the problem with just {grid} plotting informs me that the issue isn't necessarily in ggsave() but downstream.
If replacing ragg::agg_png() with png() also gives the same problem, that would mean the problem also probably is not in {ragg} either.

[mlaparie]

Thanks. I'll check png() later and if it does indeed give the same problem, I'll close here and report the bug to Guix (with an URL here for your information).

[teunbrand]

Thanks for checking. As this seems outside of ggplot2's control, I'll agree with closing this issue here.