[R] pdf() device uses fonts to represent points - data alteration?
jo.irisson at gmail.com
Thu Oct 4 10:21:28 CEST 2007
I discovered that the pdf device uses fonts to represent "points"
symbols (as in plot(...,type="p",...) ). Namely it uses ZapfDingbats
with symbol U+25cf. This can lead to problems when the font is not
available, or available in another version (such as points being
replaced by other symbols, or worst: slightly displaced).
Furthermore, it also causes problems when opening the pdf files for
editing in other programs. I know that for reproducibility one should
avoid doing this but there are cases where R is simply not suited to
produce the end result graphic directly using code (Ex: replace some
colors by CMYK versions for color consistency in print). In addition,
publishers also often like being able to retouch graphics to ensure
fonts consistency or such, and this will be destructive in the case
of these pdfs. For example, Inkscape interprets points as squares
(more like U+2751 in ZapfDingbats) and Adobe Illustrator does not
even recognize the font (substituting AdobePiStd).
I tried to embed fonts with embedFonts() but his does not solves the
issue with editing (Inkscape produces a kind of star and AI still
chokes on the font) and worst, it modifies how the original graphic
renders in pdf viewers: the circles are now filled (I believe this is
because this is the default state of the ZapfDingbats character).
So my questions are:
- does anyone have a work around this?
- why can't the pdf device use shapes instead of fonts to represent
data point? It would appear as a much more robust approach and would
ensure that the points are rendered the same everywhere. Font
substitution in axes labels is not as bad since it does not modify
the data itself (at worst the labels are offset a little bit) but
font substitution on the data points can really harm the graphic.
Examples of code:
visualize the fonts:
and a package with the two pdf files and bitmaps of how they render
or are interpreted in various programs:
Thank you in advance for your attention and help.
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