Search code examples
rsweave

Sweave - using a variable from Latex into code chunks

I need to use variable (ie. an argument of a custom command) from latex into a R inline code chunk. See, for instance :

\newcommand{\textvar}[1]{
  \textbf{
    \Sexpr{
       # Here, I would like to use the one argument of my \textvar command to do somthing in R
    }
  }
}

Of course, I can't just add #1 like in pure Tex, it would just comment the line in R.

Solution

  • You can't do that because of the order in which things are run. First Sweave() processes the .Rnw file to produce a .tex file, then LaTeX processes the .tex file to produce output. Sweave (and hence R) knows nothing about LaTeX macro processing.

    What you could do is write an R function that outputs the LaTeX you want, e.g. something like

    textvar <- function(x) {
   paste0("\\textbf{", x, "}")
}

    and then insert this as an inline code chunk

    \Sexpr{textvar(x)}

    which will expand to the LaTeX code you want your \textvar macro to insert.