[R-sig-Debian] problem with `viridis` on Ubuntu 20.04

[Samuele Carcagno]

Il 30/04/20 01:39, Dirk Eddelbuettel ha scritto:
> 
> On 30 April 2020 at 01:24, Samuele Carcagno wrote:
> | I've hit a bug on Ubuntu 20.04. The issue occurred both with the R
> | version that shipped with Ubuntu last week, and it is occurring now with
> | the CRAN packages from one of the mirros (deb
> | http://cran.mirror.garr.it/mirrors/CRAN/bin/linux/ubuntu/
> | focal-cran40/). The issue occurs whether I use the deb package for
> | viridis in the Ubuntu repos, or I install it with `install.packages()` in R.
> |
> | The issue is that when I call a function from the 'viridis' package
> | (e.g. running the first example in the `viridis` vignette:
> | https://cran.r-project.org/web/packages/viridis/vignettes/intro-to-viridis.html)
> | R gets stuck indefinitely; the system monitor shows the R process using
> | CPU resources but nothing happens at the terminal and I'm also unable to
> | stop the function with Ctrl-C.
> |
> | I did a little digging and simply calling the function `viridis` from
> | the `viridisLite` package causes the same problem, execution gets stuck
> | at the line:
> |
> |      cols <- fn_cols(seq(begin, end, length.out = n)) / 255
> |
> | which is line 177 here:
> | https://github.com/sjmgarnier/viridisLite/blob/master/R/viridis.R#L177
> |
> | I'm dual booting Debian Buster on the same machine and no such issue
> | occurs with R 4.0.0 and the same versions of the `viridis` and
> | `viridisLite` packages. Also no such issue occurs on Windows 10 or on a
> | Mac both with R 4.0.0 and the latest versions of `viridis` and
> | `viridisLite`.
> |
> | I was not sure where should I report the bug, so I thought of asking for
> | advice here first.
> 
> Can we make it reproducible, please?  Can you provide a minimal script with
> values for begin, end, n, ... etc pp or a concrete call?
> 
> I got lost in your description above between what version of R from where you
> ran with which package or function.
> 
> Keep. It. Simple. And. Concise.
> 
> And reproducible.

I've attached a script that triggers the bug on my system. It's just two 
lines, one to load `viridisLite`, and one to call the `viridis` 
function. I've also attached the output of `sessionInfo`.

To sum up all the additional info in my previous e-mail: the bug occurs 
on Ubuntu 20.04 with R 4.0.0, but does not occur on Debian, Windows, or 
Mac using the same version of R (R 4.0.0), and the same version of 
viridisLite.

Best,

Sam

> 
> For what it is worth, it _works for me with R 4.0.0 on Ubuntu 19.10_ with the
> binary .deb from my PPA (as blogged about, but should be identical to what
> Michael built and ships via CRAN).  Log of a fresh Emacs session below. I
> double Ubuntu 20.04 is different but "one never knows".
> 
> Thank you!
> 
> Dirk
> 
> Log below
> 
> R version 4.0.0 (2020-04-24) -- "Arbor Day"
> Copyright (C) 2020 The R Foundation for Statistical Computing
> Platform: x86_64-pc-linux-gnu (64-bit)
> 
> R is free software and comes with ABSOLUTELY NO WARRANTY.
> You are welcome to redistribute it under certain conditions.
> Type 'license()' or 'licence()' for distribution details.
> 
>    Natural language support but running in an English locale
> 
> R is a collaborative project with many contributors.
> Type 'contributors()' for more information and
> 'citation()' on how to cite R or R packages in publications.
> 
> Type 'demo()' for some demos, 'help()' for on-line help, or
> 'help.start()' for an HTML browser interface to help.
> Type 'q()' to quit R.
> 
> 
> There's an informal tradition that those announcements [about R releases] contain at least one mistake, but apparently I forgot this time, so users have to make up their own....
>     -- Peter Dalgaard (about an apparent non-bug report in his former R-announce message)
>        R-help (December 2009)
> 
> R> setwd('/home/edd/')
> R>
> R> library(viridisLite)
> R> example(viridis)
> 
> viridsR> library(ggplot2)
> 
> viridsR> library(hexbin)
> 
> viridsR> dat <- data.frame(x = rnorm(10000), y = rnorm(10000))
> 
> viridsR> ggplot(dat, aes(x = x, y = y)) +
> virids+   geom_hex() + coord_fixed() +
> virids+   scale_fill_gradientn(colours = viridis(256, option = "D"))
> Hit <Return> to see next plot:
> 
> viridsR> # using code from RColorBrewer to demo the palette
> viridsR> n = 200
> 
> viridsR> image(
> virids+   1:n, 1, as.matrix(1:n),
> virids+   col = viridis(n, option = "D"),
> virids+   xlab = "viridis n", ylab = "", xaxt = "n", yaxt = "n", bty = "n"
> virids+ )
> Hit <Return> to see next plot:
> R>
> 

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