[R] Plotmath and line breaks in long annotations for plots

[David Hewitt]

I'm trying to combine multi-line text and math annotations on a plot
and am not having much luck. I looked at various suggestions in the
archives, but I cannot coerce any of them to do what I want. I'm
beginning (finally?!) to think that there is an entirely better
approach than the one I have tried.

The essential problem is that line breaks (\n) don't seem to behave
the way I expected when combined with text strings and plotmath in a
call to text(). My vision for the annotation, which may be a little
beyond the norm, is to have a series of centered lines of text
somewhere on the plot that includes various object values and symbols.
I'd like to wrap it all up in one call to text() so that it has a
common anchor. Here is an example:

a <- c(1, 10)
b <- c(1, 10)
amean <- mean(a)
bmean <- mean(b)

plot(a, b)

# Annotation with paste()
text(amean, bmean,
   bquote(paste("Here are the values\nI want to write on the plot\n\n",
      amean==.(amean), "\nand\n", bmean==.(bmean))))

# Annotation without paste()
text(amean, bmean,
   bquote('Here are the values\nI want to write on the
plot\n\n'~amean==.(amean)~'\nand\n'~bmean==.(bmean)))

Another suggestion in the archives involved creating a list with the
strings that were then passed through parse(), but that did not work
either.

Corrections, suggestions, or redirections greatly appreciated.
-- 
Dave Hewitt
Research Fishery Biologist
US Geological Survey, Klamath Falls, OR, USA