Save a plot to multiple formats

Saves a ggplot object to disk at a set physical size. Allows specific maximum dimensions with an optional target aspect ratio to fit into specific configurations for publication. e.g. a half page plot or a third of a 2 column page. Allows output in pdf for journal publication or png for inclusion in documents, and makes sure that the outputs are near identical.

Usage

.gg_save_as(
  plot,
  filename = tempfile(),
  size = std_size$half,
  maxWidth = size$width,
  maxHeight = size$height,
  aspectRatio = maxWidth/maxHeight,
  formats = getOption("ggrrr.formats", default = c("svg", "png", "pdf")),
  webfontFinder = ~return(list()),
  ...
)

Arguments

plot

a ggplot

filename

base of target filename (excluding extension).

size

a standard size see std_size

maxWidth

maximum width in inches

maxHeight

maximum height in inches

aspectRatio

defaults to maxWidth/maxHeight

formats

some of svg, png, pdf, Rdata, eps, ...

webfontFinder

a function that takes a plot and returns a properly formatted css specification for webfonts in the plot. This is for internal use and does not need to be changed.

...

Named arguments passed on to svglite::svglite

pointsize

Default point size.

standalone

Produce a standalone svg file? If FALSE, omits xml header and default namespace.

id

A character vector of ids to assign to the generated SVG's. If creating more SVG files than supplied ids the exceeding SVG's will not have an id tag and a warning will be thrown.

fix_text_size

Should the width of strings be fixed so that it doesn't change between svg renderers depending on their font rendering? Defaults to TRUE. If TRUE each string will have the textLength CSS property set to the width calculated by systemfonts and lengthAdjust='spacingAndGlyphs'. Setting this to FALSE can be beneficial for heavy post-processing that may change content or style of strings, but may lead to inconsistencies between strings and graphic elements that depend on the dimensions of the string (e.g. label borders and background).

scaling

A scaling factor to apply to the rendered line width and text size. Useful for getting the right sizing at the dimension that you need.

always_valid

Should the svgfile be a valid svg file while it is being written to? Setting this to TRUE will incur a considerable performance hit (>50% additional rendering time) so this should only be set to TRUE if the file is being parsed while it is still being written to.

file

Identical to filename. Provided for backward compatibility.

Value

the output is an sensible default object that can be displayed given the context it is called in, for example if knitting an RMarkdown document a link to the png file for embedding, if latex a link to the pdf file.

Details

For maximum cross platform reproducibility we are using the combination of systemfonts for font management, svglite to render the canonical output rsvg to convert that to pdf, and ragg for bitmap formats. In some situations rsvg fails in which case we fall back to rendering in a headless chrome instance. This rather complicated pipeline ensures modern webfont support, and editable SVG or PDF.

Unit tests

.gg_pedantic(fontSize = 6)
p = ggplot2::ggplot(mtcars, ggplot2::aes(mpg, wt, colour=as.factor(cyl))) +
  ggplot2::geom_point()
# p %>% .gg_save_as(filename="~/tmp/plot_example",maxWidth=4,maxHeight=4)
p %>% .gg_save_as(filename=tempfile(),maxWidth=2,maxHeight=1.5)

plot = ggplot2::ggplot(ggplot2::diamonds, ggplot2::aes(x=carat,y=price,color = color))+
  ggplot2::geom_point()+
  ggplot2::annotate("label",x=2,y=10000,label="Hello \u2014 world", family="Kings")+
  ggplot2::labs(tag = "A")+
  ggplot2::xlab("Carat\u2082")+
  ggplot2::ylab("price\u2265")

# plot %>% .gg_save_as(filename="~/tmp/plot_example_2")
res = plot %>% .gg_save_as(filename=tempfile(), formats=c("png","eps"))
as.character(res)
res