[R] How do you specify font family in png output; png cross-platform issues

[Paul Johnson]

For teaching purposes, I prepared a little R program. I want to give
this to students who can run it and dump out many formats and then
compare their use in LaTeX documents.  I do not have too much trouble
with xfig or postscript format, but I've really run into a roadblock
where png files are concerned.

My original problem was that the png device does not accept a family option.
How can I have png output with the "Times" family to compare with the
postscript or pdf output?

While searching for information on this, I discovered there have been
a lot of R changes in png support.  If I give this script to people
with Mac or Windows, what are the chances that it will work?  If I'm
reading the png help page correctly, there are different types
available, Xlib and cairo, but I don't understand what all that means
for sending a program like this across systems. (fear the worst, but
ask hoping for best).

As far as I understand it, the paper="special" option is needed so
that the eps or pdf output will fit into a document without creating
really huge margins around the graph. Correct?


x<- rnorm(333)

y<- rnorm(333)

plot ( x,y, xlab="Input Variable", ylab="Output Variable")

xfig(file="testplot.fig",  horizontal=F, height=6, width=6, family="Times")
plot ( x,y, xlab="Input Variable", ylab="Output Variable")
dev.off()

postscript(file="testplot-1.eps",  horizontal=F, height=6, width=6,
family="Times", onefile=F, paper="special")
plot ( x,y, xlab="Input Variable", ylab="Output Variable")
dev.off()

postscript(file="testplot-2.eps",  horizontal=F, height=4, width=4,
family="Times", onefile=F, paper="special")
plot ( x,y, xlab="Input Variable", ylab="Output Variable")
dev.off()

pdf(file="testplot-1.pdf", height=6, width=6,
family="Times",onefile=F,paper="special")
plot ( x,y, xlab="Input Variable", ylab="Output Variable")
dev.off()


png(file="testplot-1.png", height=350, width=550, type="Xlib")
plot ( x,y, xlab="Input Variable", ylab="Output Variable")
dev.off()


png(file="testplot-2.png", height=350, width=550, type="cairo")
plot ( x,y, xlab="Input Variable", ylab="Output Variable")
dev.off()

============================================


Can I bother you about one last png issue?

While searching r-help, I see posts about the difference in png output
between type Xlib and cairo.  For reasons I do not understand,
ordinary viewers like GQview or Firefox make cairo-produced png files
look "blurry" (in the words of posts on r-help).  The png output from
type="Xlib" output is not blurry. This raises another level of
confusion about this exercise I'm devising.  Does R for Windows, as
provided on the CRAN system, use "Xlib" for png?

pj



-- 
Paul E. Johnson
Professor, Political Science
1541 Lilac Lane, Room 504
University of Kansas