Issue with x11() and font in R

Question

I am having problems changing font in R. For some reasons, it seems that R can not find the font I am asking (any of them, actually). I double-checked that the fonts are indeed installed on my system (Linux Mint 20.3). It looks like to be related to x11(), but it appears to be supported on my machine.

Any ideas appreciated.

capabilities()
#>        jpeg         png        tiff       tcltk         X11        aqua 
#>        TRUE        TRUE        TRUE       FALSE        TRUE       FALSE 
#>    http/ftp     sockets      libxml        fifo      cledit       iconv 
#>        TRUE        TRUE        TRUE        TRUE       FALSE        TRUE 
#>         NLS       Rprof     profmem       cairo         ICU long.double 
#>        TRUE        TRUE       FALSE        TRUE        TRUE        TRUE 
#>     libcurl 
#>        TRUE

library(ggplot2)

ggplot() +
  labs(x = quote(delta)) +
  theme(text = element_text(family = "Roboto"))
#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database

#> Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family not
#> found in X11 font database
#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database

#> Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
#> family not found in X11 font database
#> Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
#> font family not found in X11 font database

#> Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
#> font family not found in X11 font database

#> Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
#> font family not found in X11 font database

#> Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
#> font family not found in X11 font database

#> Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
#> font family not found in X11 font database

^{Created on 2022-01-18 by the reprex package (v2.0.1)}

Answer 1

Here's what I did after following my own (slightly misspelled) advice:

?X11Fonts

The followed the example and executed its code:

if(capabilities()[["X11"]]) withAutoprint({
X11Fonts()
X11Fonts("mono")
utopia <- X11Font("-*-utopia-*-*-*-*-*-*-*-*-*-*-*-*")
X11Fonts(utopia = utopia)
})

No error and "utopia" was there in the listed fonts the next time I ran X11Fonts(), so I tried with "Roboto" (in an Ubuntu 18.04 box).

 Roboto <- X11Font("-*-roboto-*-*-*-*-*-*-*-*-*-*-*-*")
 X11Fonts(Roboto = Roboto)
#-------------------
> X11Fonts()
$serif
[1] "-*-times-%s-%s-*-*-%d-*-*-*-*-*-*-*"

$sans
[1] "-*-helvetica-%s-%s-*-*-%d-*-*-*-*-*-*-*"


#---snipped

$Roboto
[1] "-*-roboto-%s-%s-*-*-%d-*-*-*-*-*-*-*"

Looks like Roboto is now mine. (I have no idea what it looks like.)

After executing:

 library(ggplot2)

ggplot() +
  labs(x = quote(delta)) +
  theme(text = element_text(family = "Roboto"))

.... I now see an unmarkerked plot area with a Greek lowercase delta as the label in an x11 window, which will disappear after I execute dev.off().