Adding a single backslash (\) to a string in R

Question

I am working on knitr right now, One of the string that I was trying to print has the % symbol. I read up on the TeX manual that to a print the % symbol. TeX should have the string as \% to display the code.

Using the command gsub I tried to do the following:

try = "0% success"
try2 = gsub("%","\%",try,fixed = TRUE)

gsub throws an invalid escape character error

If I do this:

try = "0% success
try2 = gsub("%","\\\\%",try,fixed = TRUE)

knitr will still not be able to print the string

Please suggest me with a way that I can solve my problem

--------EDIT------------------

I want the string in try to displayed as it is in my output PDF I am using this in knitr as \textit{\Sexpr{try}} When the tex file gets created, it believes that the text after percentage is a comment. I am creating an rnw file first and then creating the tex file, after which using texi2pdf to get the pdf file

----EDIT 2 -------------

I am not very good with either knitr or LaTeX

Answer 1

why are you jumping fomr one "\" to 4 "\"?

> try2 = gsub("%","\\%",try,fixed = TRUE)
> try2
[1] "0\\% success"

This should be read as "\\", which (as far as i know) the regular expression will understand as an "\".

I hope i understood you right- and this is a possible sulution for you!

Answer 2

You need two backslashes to escape:

<<>>=
try = "0\\% success"
@

Some text in LaTex \Sexpr{try}. 

After knitting the document one obtains the following LaTeX code:

\begin{document}

\begin{knitrout}
\definecolor{shadecolor}{rgb}{0.969, 0.969, 0.969}\color{fgcolor}\begin{kframe}
\begin{alltt}
\hlstd{try} \hlkwb{=} \hlstr{"0\textbackslash{}\textbackslash{}% success"}
\end{alltt}
\end{kframe}
\end{knitrout}

Some text 0\% success

\end{document}

This, of course, assuming echo=TRUE.