[R] extracting items from R objects and using them in \Sexpr with Sweave--problem with $

Christopher W. Ryan cryan at binghamton.edu
Thu Nov 29 20:45:35 CET 2007

Running R 2.5.1 on WinXP with Tinn-R, and using Sweave via MikTex.

I am having trouble with the code below:

lowerCI95713 <- t.test(data713, alternative="greater")
lowerCI95713.bound <- lowerCI95713$conf.int[1]

Thus a lower 95\% confidence bound on the mean octane concentration is

t.test713 <- t.test(data713, mu=87, alternative="greater")
p.value <- t.test713$p.value


When I Sweave and then pdflatex the files, the output pdf file contains
the verbatim text:

"Thus a lower 95% confidence bound on the mean octane concentration is

That is, LaTeX is not recognizing and processing \Sexpr.  When I look at
my .tex file in an editor with LaTeX syntax highlighting, I see that
LaTeX is interpreting everything between the two $ in the original code
(one before conf.int and one before p.value) as a math environment.  I
think that's why the \Sexpr is not getting processed into the single
number as it should.

Any ideas how to make this work?  The $ is the only way I know how to
access components of R objects.

Thank you.

Christopher W. Ryan, MD
SUNY Upstate Medical University Clinical Campus at Binghamton
40 Arch Street, Johnson City, NY  13790
PGP public keys available at http://home.stny.rr.com/ryancw/

"If you want to build a ship, don't drum up the men to gather wood,
divide the work and give orders. Instead, teach them to yearn for the
vast and endless sea."  [Antoine de St. Exupery]

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