how to control default packages loaded by RMarkdown/knitr to avoid option clash

Question

I use r markdown with knitr to produce tex documents. However, On several occasions I have run into an issue where the packages I am loading with the "mystyles.txt" document in the preamble conflict with packages that are loaded automatically by knitr. The error looks different depending on the issue but it is always characterized by an "option clash".

I believe I understand where this problem is coming from (I think) -- I just don't know how to fix it. When I try to use a package in mystyles.txt such as \usepackage[pdftex]{graphicx} or \usepackage[table]{xcolor}, I get the option clash error because these package have already been loaded WITHOUT options by default.

However, this presents an issue because I need to load the packages with the exact options I specified. Which means that somehow I need to supress or modify the package loading done automatically by r markdown/knitr.

For example, knitr automatically calls \usepackage{graphicx}. If there was some way to specify in the preamble so that this was instead \usepackage[pdftex]{graphicx}, then I could just remove the identical line from mystyles.txt, and I would be good. Unfortunately, I have not been able to find any documentation of this issue, and the following reference guide does not provide any insights: http://rmarkdown.rstudio.com/RMarkdownReferenceGuide.pdf.

Does anyone know how to deal with this problem?

-Paul

Answer 1

I just had this problem this morning and my solution was to use a custom template.

This document explains the various options for PDF output and you'll see that there is one for setting a custom template about 1/3 of the way down with an example YAML header:

---
title: "My document"
output:
  pdf_document:
    template: my_template.tex
---

You then need to create the my_template.tex template file. The previous page links to the default template used by Knitr; just copy and paste this into my_template.tex file and remove the conflicting bits of code.

Here's a minimal template that I found worked for me.

\documentclass[$if(fontsize)$$fontsize$,$endif$$if(lang)$$babel-lang$,$endif$$if(papersize)$$papersize$,$endif$$for(classoption)$$classoption$$sep$,$endfor$]{$documentclass$}

\usepackage{hyperref}
\hypersetup{unicode=true,
$if(title-meta)$
            pdftitle={$title-meta$},
$endif$
$if(author-meta)$
            pdfauthor={$author-meta$},
$endif$
$if(subtitle)$
            pdfsubject={$subtitle$},
$endif$
$if(keywords)$
            pdfkeywords={$for(keywords)$$keywords$$sep$; $endfor$},
$endif$
$if(colorlinks)$
            colorlinks=true,
            linkcolor=$if(linkcolor)$$linkcolor$$else$Maroon$endif$,
            citecolor=$if(citecolor)$$citecolor$$else$Blue$endif$,
            urlcolor=$if(urlcolor)$$urlcolor$$else$Blue$endif$,
$else$
            pdfborder={0 0 0},
$endif$
            breaklinks=true}
\urlstyle{same}  % don't use monospace font for urls
$if(listings)$
\usepackage{listings}
$endif$
$if(lhs)$
\lstnewenvironment{code}{\lstset{language=Haskell,basicstyle=\small\ttfamily}}{}
$endif$
$if(highlighting-macros)$
$highlighting-macros$
$endif$
$if(verbatim-in-note)$
\usepackage{fancyvrb}
\VerbatimFootnotes % allows verbatim text in footnotes
$endif$
$if(tables)$
\usepackage{longtable,booktabs}
$endif$
$if(graphics)$
\usepackage{graphicx,grffile}
\makeatletter
\def\maxwidth{\ifdim\Gin@nat@width>\linewidth\linewidth\else\Gin@nat@width\fi}
\def\maxheight{\ifdim\Gin@nat@height>\textheight\textheight\else\Gin@nat@height\fi}
\makeatother
% Scale images if necessary, so that they will not overflow the page
% margins by default, and it is still possible to overwrite the defaults
% using explicit options in \includegraphics[width, height, ...]{}
\setkeys{Gin}{width=\maxwidth,height=\maxheight,keepaspectratio}
$endif$
$if(links-as-notes)$
% Make links footnotes instead of hotlinks:
\renewcommand{\href}[2]{#2\footnote{\url{#1}}}
$endif$
$if(strikeout)$
\usepackage[normalem]{ulem}
% avoid problems with \sout in headers with hyperref:
\pdfstringdefDisableCommands{\renewcommand{\sout}{}}
$endif$

$if(title)$
\title{$title$$if(subtitle)$\\\vspace{0.5em}{\large $subtitle$}$endif$}
$endif$
$if(author)$
\author{$for(author)$$author$$sep$ \and $endfor$}
$endif$
\date{$date$}
$for(header-includes)$
$header-includes$
$endfor$

$if(subparagraph)$
$else$
% Redefines (sub)paragraphs to behave more like sections
\ifx\paragraph\undefined\else
\let\oldparagraph\paragraph
\renewcommand{\paragraph}[1]{\oldparagraph{#1}\mbox{}}
\fi
\ifx\subparagraph\undefined\else
\let\oldsubparagraph\subparagraph
\renewcommand{\subparagraph}[1]{\oldsubparagraph{#1}\mbox{}}
\fi
$endif$

\begin{document}
$if(title)$
\maketitle
$endif$
$if(abstract)$
\begin{abstract}
$abstract$
\end{abstract}
$endif$

$for(include-before)$
$include-before$

$endfor$
$if(toc)$
{
$if(colorlinks)$
\hypersetup{linkcolor=$if(toccolor)$$toccolor$$else$black$endif$}
$endif$
\setcounter{tocdepth}{$toc-depth$}
\tableofcontents
}
$endif$
$if(lot)$
\listoftables
$endif$
$if(lof)$
\listoffigures
$endif$
$body$

$if(natbib)$
$if(bibliography)$
$if(biblio-title)$
$if(book-class)$
\renewcommand\bibname{$biblio-title$}
$else$
\renewcommand\refname{$biblio-title$}
$endif$
$endif$
\bibliography{$for(bibliography)$$bibliography$$sep$,$endfor$}

$endif$
$endif$
$if(biblatex)$
\printbibliography$if(biblio-title)$[title=$biblio-title$]$endif$

$endif$
$for(include-after)$
$include-after$

$endfor$
\end{document}