[R] Plots: displaying mathematical symbols in specific fonts

[Prof Brian Ripley]

On Mon, 20 Feb 2006, Ed Merkle wrote:

> Dear SavioRs,
>
> I am doing some research where characters in different microsoft
> fonts serve as experimental stimuli.  Hence, in plot labels, I would
> like to display the characters in specific microsoft fonts.  I have
> figured out how to display letters and numbers, but I am having
> trouble with symbols such as capital delta.  Before I go further, I
> am using R 2.2.1 on Windows XP with everything in English.  I am
> trying to save my plot as a windows metafile.
>
> To display different characters in verdana, for example, I first edit
> the Rdevga file so that it contains verdana.  I can then get verdana
> letters and numbers on the plot using a text() command.  Things
> within an expression() command, however, are not displayed in the
> desired font.  For example,

No, they are *always* displayed in font 5, as the Rdevga file actually 
says.  Verdana is not a mathematical font, and what you are looking for is 
the Greek letter Delta, not the mathematical symbol.

> windows()
> plot(rnorm(15),rnorm(15))
> text(0,0,expression(Delta),font=10)
>
> displays a capital delta, but it is not in font #10 within Rdevga.  I
> can get characters that have one of the first 255 ascii codes

Hmm, there are only 128 ASCII codes.  I guess you mean you are in CP1252 
aka WinAnsi, the Windows approximation to ISO Latin-1, and so can only 
access the (somewhat less than) 256 glyphs of that charset.

> using
> chars8bit() in the sfsmisc package.  One example is the division sign:
>
> text(0,0.2,chars8bit(247),font=10)

You don't need that: the standard octal and hex escapes work.  But if you 
want to draw symbols you should probably be using points() and pch=.
E.g.

points(0, 0.2, font=10, pch=247)

> I have not been able to display other symbols in microsoft fonts,
> however.  Is this possible to do in R?  All replies are appreciated.

Yes, but only by switching to a Greek locale.  For example

Sys.setlocale("LC_CTYPE", "greek")
plot(1:10)
text(8,2, "\xC4", font=10)

and that only on an NT-based version of Windows and the R-devel version of 
R.

It's easier on Unix-alikes in a UTF-8 locale, as then you can use Unicode 
escapes like \u0394.  But Windows does not have UTF-8 locales (although 
one day R may fake them -- actually internally it already can but there is 
no I/O support).  There you could also do

text(8, 2, "\u0394")
points(5, 7, font=4, pch=0x0394)

at least if you have fonts which support Greek.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595