[R] Trouble combining plotmath, bquote, expressions

[Paul Johnson]

I'm using R-2.6.2 on Fedora Linux 9.

I've been experimenting with plotmath.

I wish it were easier to combine expressions in plotmath with values
from the R program itself.  There are two parameters in the following
example, the mean "mymean" and standard deviation "mystd".  I am able
to use bquote to write elements into the graph title like

mu = mymean

and R will plot the symbol "mu" and the value of mymean from the
program. But I want to combine that result in a string along with
other results.

Can I combine to result like this

"Normal( mu = mymean , sigma = mystd)"

Where symbols mu and sigma are replaced with Greek and mymean and
mystd are drawn from program?


### Filename: Normal1_2008.R
### Paul Johnson March 31, 2008
### This code should be available somewhere in
http://pj.freefaculty.org.  If it is not
### email me <pauljohn at ku.edu>

mymean <- 0
mystd <- 1.5
myx <- seq( mymean - 3*mystd,  mymean+ 3*mystd, length.out=500)


myDensity <- dnorm(myx,mean=mymean,sd=mystd)

## This works
plot(myx, myDensity, type="n", xlab="X", ylab="Probability Density ",
main=expression(mu == 0))
## This works
plot(myx, myDensity, type="n", xlab="X", ylab="Probability Density ",
main=expression(sigma == 1.5))

## This works
t1 <-  bquote( mu== .(mymean))

plot(myx, myDensity, type="n", xlab="X", ylab="Probability Density ", main= t1 )

## This works

t2 <-  bquote( sigma== .(mystd))

plot(myx, myDensity, type="n", xlab="X", ylab="Probability Density ", main=t2)

## Can't figure how to combine t1 and t2 into plot title

### This fails!
### plot(myx, myDensity, type="n", xlab="X", ylab="Probability Density
", main=paste( t1,t2) )


plot(myx, myDensity, type="n", xlab="X", ylab="Probability Density ", main= t1 )

## Can drop sigma in as margin text, though, on side 3.
mtext(t2, 3)
lines(myx,myDensity,lty=4, col=4) ### change line type & color if you want

############################

Supposing there is a way to do this, could I submit a working example
to be added to the help page for plotmath ?  How could I go about
that?


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