[R] Text position in Traditional Graphics

[Charles Annis, P.E.]

A few days a go Jim Holman [jholtman at gmail.com] suggested this
(Re: [R] How to annotate a graph with non-transparent math labels?)
for a similar circumstance.  Perhaps it will for in your case.

~~~~~~~~~~~~~~~~
try using strwidth & strheight

x<-c(0,1)
plot(x,x,type='l')
dimensions<-matrix(c(strwidth(expression(theta),cex=5),strheight(expression(
theta),
cex=5)),nrow=1)
symbols(0.5,0.5
,rectangle=dimensions,bg='white',fg='white',add=TRUE,inches=FALSE)
text(0.5,0.5,expression(theta),cex=5)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



Charles Annis, P.E.

Charles.Annis at StatisticalEngineering.com
phone: 561-352-9699
eFax:  614-455-3265
http://www.StatisticalEngineering.com
 

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Mike Prager
Sent: Wednesday, January 24, 2007 4:30 PM
To: r-help at stat.math.ethz.ch
Subject: [R] Text position in Traditional Graphics

R 2.4.1 on Windows XP.

Question:  In traditional graphics, is it possible to find out
the height of a line of text in units that can be used in
arithmetic and then in calls to text()? 

Context:  I have written a function that draws a plot and then,
depending on whether some arguments are TRUE or FALSE, draws
various lines of text in the plot. The text lines may be turned
on or off individually by the user. The function uses plot() and
several calls to text().

However, I have not found a good way to adjust the Y coordinate
of the text for lines after the first. I would like this to work
when the graphics device (windows) is opened at (or resized to)
a wide range of sizes.  The issue is that a line of text takes
up a smaller fraction of the total Y span of the plotting region
as the window gets larger.

It seems this can be done with grid graphics, but although I
plan to learn grid, I am hoping that for now, I can do this work
with traditional graphics.

Thanks!

-- 
Mike Prager, NOAA, Beaufort, NC
* Opinions expressed are personal and not represented otherwise.
* Any use of tradenames does not constitute a NOAA endorsement.

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