\documentclass[11pt]{article}
\usepackage{verbatim}
\usepackage{lmodern}
\usepackage[utf8]{inputenc}
\usepackage[margin=0.5in]{geometry}
\usepackage{url}
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\begin{document} 
\paragraph{The R environment for computing and graphics.}

This follows the 
\texttt{Sweave}
example at 
\url{http://jacobwegelin.net/prn/20120718Wed143201/},
with modifications so that we can use the 
\texttt{knitr}
package instead of 
\texttt{Sweave}.

Suppose you have a table (or matrix or dataframe) with a lot of text in a cell, such as the following. 
<<defineStuff, echo=TRUE, tidy=FALSE>>=
library(knitr)
library(xtable)
library(tools)
set.seed(5)
bigmess<- 
data.frame(
freeText=c("I have done the state some service and they know it. No more of that. I pray you, in your letters, When you shall these unlucky deeds relate, Speak of me as I am. Nothing extenuate, Nor set down aught in malice."
, "ignotumque sibi mentula discat opus" 
, "denique cum membris conlatis flore fruuntur aetatis, iam cum praesagit gaudia corpus"
, "cum dicis propero fac si facis Hedyle languet protinus et cessat debilitata Venus. exspectare jube. velocius ibo retentus.")
, x=sample(1:199, size=4, replace=FALSE))
bigmess$group<- sample(LETTERS, replace=TRUE, size= nrow(bigmess))
# Note that bigmess has three variables (columns):
names(bigmess)
@

In knitr let's display the table. 
First we demonstrate that in knitr,
the option ``results=`markup'{}'' is kinda like specifying the verbatim environment in \LaTeX{}.
This is not what we want:
<<echo=TRUE, eval=TRUE, results='markup'>>=
tmess<-xtable(as.matrix( bigmess))
print(tmess, include.rownames=FALSE)
@

We will change to ``results=`asis'{}'' to get the table to display in \LaTeX{}. 
But when we 
``naïvely'' use xtable with the default values for print(), the table marches off the page and we don't even see all of the first column:
<<echo=TRUE, eval=TRUE, results='asis'>>=
tmess<-xtable(as.matrix( bigmess))
print(tmess, include.rownames=FALSE)
@
\clearpage{}
To remedy this, 
we'd like to squeeze or squish 
(depending on which part of the English-speaking world we're from)
the ``freeText'' column into a ``multicolumn'' situation (in \LaTeX{} lingo),
which is like opening a spreadsheet in Excel\textregistered{},
highlighting the first column, specifying ``wrap text'', and messing around with the mouse---but
much better, because automated and reproducible. 

<<multirow-wraptext2, eval=TRUE, results='asis', echo=TRUE>>=
align(tmess) <- c("r", "p{3.5in}", "c", "c")
print(tmess, include.rownames=FALSE)
@
But now let's run an identical chunk, except that ``echo=FALSE''. 
<<multirow-wraptext, eval=TRUE, results='asis', echo=FALSE>>=
align(tmess) <- c("r", "p{3.5in}", "c", "c")
print(tmess, include.rownames=FALSE)
@

The fine print:
<<sessionInfo, eval=TRUE, echo=TRUE>>=
# knit("knitfoo.Rnw")
#
# texi2dvi("knitfoo.tex", pdf = TRUE)
sessionInfo()
@
\end{document}