ragg device functions not working with ggsave

[PaulC91]

In the recent tidyverse blogpost "Modern Text Features in R" it states you can use the ragg device functions with ggsave:

You can use ragg with ggsave() by passing the device function to the device argument (e.g. ggsave(device = agg_tiff)).

It's not working for me however, the following code results in an empty image being saved.

Related to r-lib/ragg#69

library(ggplot2)
library(ragg)

p <- ggplot(iris, aes(Sepal.Length, Sepal.Width, col = Species)) + geom_point() 

ggsave("gg_test.png", p, device = agg_png) 
#> Saving 7 x 5 in image

^{Created on 2021-02-17 by the reprex package (v1.0.0)}

Session info

sessioninfo::session_info()
#> ─ Session info ───────────────────────────────────────────────────────────────
#>  setting  value                       
#>  version  R version 4.0.3 (2020-10-10)
#>  os       macOS Mojave 10.14.6        
#>  system   x86_64, darwin17.0          
#>  ui       X11                         
#>  language (EN)                        
#>  collate  en_GB.UTF-8                 
#>  ctype    en_GB.UTF-8                 
#>  tz       Europe/Paris                
#>  date     2021-02-17                  
#> 
#> ─ Packages ───────────────────────────────────────────────────────────────────
#>  package     * version date       lib source             
#>  assertthat    0.2.1   2019-03-21 [1] standard (@0.2.1)  
#>  backports     1.2.0   2020-11-02 [1] standard (@1.2.0)  
#>  cli           2.2.0   2020-11-20 [1] standard (@2.2.0)  
#>  colorspace    2.0-0   2020-11-11 [1] standard (@2.0-0)  
#>  crayon        1.3.4   2017-09-16 [1] standard (@1.3.4)  
#>  digest        0.6.27  2020-10-24 [1] standard (@0.6.27) 
#>  dplyr         1.0.2   2020-08-18 [1] standard (@1.0.2)  
#>  ellipsis      0.3.1   2020-05-15 [1] standard (@0.3.1)  
#>  evaluate      0.14    2019-05-28 [1] standard (@0.14)   
#>  fansi         0.4.1   2020-01-08 [1] standard (@0.4.1)  
#>  farver        2.0.3   2020-01-16 [1] standard (@2.0.3)  
#>  fs            1.5.0   2020-07-31 [1] standard (@1.5.0)  
#>  generics      0.1.0   2020-10-31 [1] standard (@0.1.0)  
#>  ggplot2     * 3.3.3   2020-12-30 [1] standard (@3.3.3)  
#>  glue          1.4.2   2020-08-27 [1] standard (@1.4.2)  
#>  gtable        0.3.0   2019-03-25 [1] standard (@0.3.0)  
#>  highr         0.8     2019-03-20 [1] standard (@0.8)    
#>  htmltools     0.5.1.1 2021-01-22 [1] standard (@0.5.1.1)
#>  knitr         1.30    2020-09-22 [1] standard (@1.30)   
#>  labeling      0.4.2   2020-10-20 [1] standard (@0.4.2)  
#>  lifecycle     0.2.0   2020-03-06 [1] standard (@0.2.0)  
#>  magrittr      2.0.1   2020-11-17 [1] standard (@2.0.1)  
#>  munsell       0.5.0   2018-06-12 [1] standard (@0.5.0)  
#>  pillar        1.4.7   2020-11-20 [1] standard (@1.4.7)  
#>  pkgconfig     2.0.3   2019-09-22 [1] standard (@2.0.3)  
#>  purrr         0.3.4   2020-04-17 [1] standard (@0.3.4)  
#>  R6            2.5.0   2020-10-28 [1] standard (@2.5.0)  
#>  ragg        * 1.1.0   2021-02-15 [1] standard (@1.1.0)  
#>  reprex        1.0.0   2021-01-27 [1] standard (@1.0.0)  
#>  rlang         0.4.10  2020-12-30 [1] standard (@0.4.10) 
#>  rmarkdown     2.5     2020-10-21 [1] standard (@2.5)    
#>  rstudioapi    0.13    2020-11-12 [1] standard (@0.13)   
#>  scales        1.1.1   2020-05-11 [1] standard (@1.1.1)  
#>  sessioninfo   1.1.1   2018-11-05 [1] standard (@1.1.1)  
#>  stringi       1.5.3   2020-09-09 [1] standard (@1.5.3)  
#>  stringr       1.4.0   2019-02-10 [1] standard (@1.4.0)  
#>  styler        1.3.2   2020-02-23 [1] standard (@1.3.2)  
#>  systemfonts   1.0.1   2021-02-09 [1] standard (@1.0.1)  
#>  textshaping   0.3.0   2021-02-10 [1] standard (@0.3.0)  
#>  tibble        3.0.4   2020-10-12 [1] standard (@3.0.4)  
#>  tidyselect    1.1.0   2020-05-11 [1] standard (@1.1.0)  
#>  vctrs         0.3.5   2020-11-17 [1] standard (@0.3.5)  
#>  withr         2.3.0   2020-09-22 [1] standard (@2.3.0)  
#>  xfun          0.19    2020-10-30 [1] standard (@0.19)   
#>  yaml          2.2.1   2020-02-01 [1] standard (@2.2.1)  
#> 
#> [1] /Library/Frameworks/R.framework/Versions/4.0/Resources/library

Thanks.

[yutannihilation]

Thanks, I too faced this problem a while ago. As the default value of ragg::agg_png()'s unit is px, which is the same as grDevices::png(), I guess ggplot2 needs some wrappers like this:

ggplot2/R/save.r

Lines 181 to 185 in dbd7d79

	png = function(...) grDevices::png(..., res = dpi, units = "in"),
	jpg = function(...) grDevices::jpeg(..., res = dpi, units = "in"),
	jpeg = function(...) grDevices::jpeg(..., res = dpi, units = "in"),
	bmp = function(...) grDevices::bmp(..., res = dpi, units = "in"),
	tiff = function(...) grDevices::tiff(..., res = dpi, units = "in")

[clauswilke]

This is the lookup table that converts file extensions into graphic devices, so it wouldn't have an effect if users specify the graphics device as a function. Instead, if they do so, they will have to set res and units manually.

However, we should change the lookup table so it uses ragg devices by default if available.

[clauswilke]

See also: #4086

[thomasp85]

Yeah — the plan is to use ragg if available for all file types where it makes sense in the next release. If someone is eager to implement the logic they should feel free but otherwise I'm on it the next time I look at ggplot2

[yutannihilation]

However, we should change the lookup table so it uses ragg devices by default if available.

Yes, what I meant was the users need to define some wrapper function like the one below. I guess a lot of people will use AGG as RStudio graphic device (as it's great) and they'll want to use the same rendering on ggsave() as well. Probably the next release will not be very soon, so I think it's meaningful to show a workaround for this here.

library(ggplot2)

p <- ggplot(iris, aes(Sepal.Length, Sepal.Width, col = Species)) + geom_point() 

# 300 is the same dpi as ggsave()'s default
png <- function(...) ragg::agg_png(..., res = 300, units = "in")
ggsave("gg_test.png", p, device = png)

[thomasp85]

The behaviour of ggsave() is quite unfortunate... ragg uses the exact same default values as grDevices::png() but still does not behave the same way

[clauswilke]

The following works just fine, though. If people want to use custom graphics devices they need to be prepared to set a few parameters correctly, I think. Maybe the real issue is to document ggsave() better, and to explain that when using a device function, some settings such as dpi or units may not work and/or may have to be set explicitly.

library(ggplot2)

p <- ggplot(iris, aes(Sepal.Length, Sepal.Width, col = Species)) + geom_point() 

ggsave("~/Desktop/gg_test.png", p, device = ragg::agg_png, res = 300, units = "in")
#> Saving 7 x 5 in image

^{Created on 2021-02-22 by the reprex package (v1.0.0)}

[taraskaduk]

@clauswilke, when I run your example, my gg_test.png file is 7x7 pixels (not inches) big and 116 bytes in size.

FWIW, p prints to Viewer just fine, it's ggsave with agg_png that saves a tiny 7x7 pixels file.

My session info:

R version 4.0.3 (2020-10-10)
Platform: x86_64-apple-darwin17.0 (64-bit)
Running under: macOS Big Sur 10.16

Matrix products: default
LAPACK: /Library/Frameworks/R.framework/Versions/4.0/Resources/lib/libRlapack.dylib

locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8

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

other attached packages:
[1] ggplot2_3.3.3

loaded via a namespace (and not attached):
 [1] magrittr_2.0.1    tidyselect_1.1.0  munsell_0.5.0     colorspace_2.0-0  R6_2.5.0         
 [6] ragg_1.1.1.9000   rlang_0.4.10      fansi_0.4.2       dplyr_1.0.5       tools_4.0.3      
[11] grid_4.0.3        gtable_0.3.0      utf8_1.1.4        DBI_1.1.1         withr_2.4.1      
[16] systemfonts_1.0.1 ellipsis_0.3.1    digest_0.6.27     assertthat_0.2.1  tibble_3.0.6     
[21] lifecycle_1.0.0   crayon_1.4.1      textshaping_0.3.1 farver_2.0.3      purrr_0.3.4      
[26] vctrs_0.3.6       glue_1.4.2        labeling_0.4.2    compiler_4.0.3    pillar_1.5.0     
[31] generics_0.1.0    scales_1.1.1      pkgconfig_2.0.3  

[collioud]

Hello,

In addition, it seems that ggsave() does not close the device when using agg_png() as device (it does when specifying 'png' as device). The following reprex ends with to the Too many open devices error.

library(ggplot2)
library(ragg)
library(glue)

data(iris)
for (i in 1:200){
  p <- ggplot(iris) + 
    geom_point(aes(Sepal.Length,Sepal.Width,color=Species))

  ggsave(glue("Plot_{i}.png"), plot=p, device=agg_png(), path="./tmp/")
}

(This is solved by explicitly calling dev.off() after ggsave())

[yutannihilation]

@collioud
What device argument accepts is a function (e.g. agg_png, function(...) agg_png(...)), not a function call (e.g. agg_png()).

[jthomasmock]

I can confirm w/ @taraskaduk that using Claus' exact code with agg_png + friends as the device returns small images, 116 bytes, 7x7 pixels.

ragg version 1.1.2

However, providing additional arguments to agg_png() appears to work fine.

ggsave(
  "gg_test.png",
  p,
  device = ragg::agg_png( 
    width = 12,
    height = 8, 
    units = "cm",
    scaling = 1,
    res = 500)
)

[clauswilke]

Ah, this makes sense. ggsave() has a units argument so it doesn't get captured by ... and thus doesn't get handed off to agg_png(). Workaround is to specify the resolution directly in px, not in inch.

[jthomasmock]

Yup!

I can confirm you can get the "expected" behavior as so, without specifying arguments inside agg_png:

ggsave(
  "gg_test.png",
  p,
  device = ragg::agg_png,
  res = 300,
  units = "in", # this is ignored by `agg_png` and it returns default of `"px"`
  height = 1200, # this is ACTUALLY pixels
  width = 1400,  # also pixels
  limitsize = FALSE # because ggplot2 thinks it's inches
)

This is still a bit tricky to read as ggsave doesn't allow for units = "px" as the argument though.