# knitr and biblatex

I'd like to create a PDF report with knitr with LaTeX-code in RStudio with biblatex for citations. However, the in-text-citations are always undefined and no bibliography is printed. The same bibliography works perfectly with a pure .tex-document stored in the same folder and containing the same citations, same path to the .bib-file etc. However, as for all references (also with hyperref) I have to compile twice. I thought this might be the problem with knitr (that the compilation is run only once), but the hyperref-references to figures work well. Any idea what might go wrong with the bibliography when using knitr and how I can solve the problem?

MWE:

\documentclass{article}

\usepackage[style=authoryear-comp, maxnames=1, bibencoding=utf8, backend=biber]{biblatex}
\bibliography{ZoteroOutput.bib}

\begin{document}

According to the literature \parencite{gonzalez2003} we can assume...

\printbibliography

\end{document}


From the log-file:

Package biblatex Warning: Please (re)run Biber on the file:
(biblatex)                mwe
(biblatex)                and rerun LaTeX afterwards.

• Show us a reproducible example. Do you have use texi2dvi enabled? rstudio.org/docs/using/customizing Sep 13 '12 at 11:04
• @RomanLuštrik I added an MWE. In the Rstudio options, I can only find Invoke compiler via texi2dvi script. I have now enabled it, but this doesn't solve the problem. Sep 13 '12 at 11:44
• The message seems to be very explicit. As a temp fix, you can run pdflatex on that .tex file again (outside Rstudio). Sep 13 '12 at 13:02
• @RomanLuštrik So there is no way to get it with one click in knitr/RStudio? That's a bit disappointing. How does it create the within-text-figure references then? As far as I know, they also need a 2nd compilation. Sep 13 '12 at 13:23
• Try running the latex output file once in miktex or what ever after ward. For me after I run it once in miktex the citations show up using Rstudio. I think this is because the encessary files are created by miktex and then can be run later when using R studio. Sep 13 '12 at 14:33

RStudio allows you to use a custom LaTeX program with that

• you can set up a script that does the proper processing
• there are automatic solutions for this, e.g. latexmk, like so: Sys.setenv(RSTUDIO_PDFLATEX = "/Library/TeX/texbin/latexmk") (or whatever you path may be)

Another option is that RStudio allows to specify build tools for a project. This may be

• either a Makefile
• or again a custom script

In addition, you may want to tell the RStudio developers about the need to have a bibliography in Sweave documents. You can tell them that I'd need it, too :-)

• Have you managed to get that to work? Aug 21 '13 at 9:57
• Here's one way to make it work for a document that has biber + biblatex + XeLaTeX + embedded R in it: mkdoc <- function(fname){ require(knitr); res <- knit(fname); if (!is.null(res)) { system2('latexmk', args=c('-xelatex', res)) } } Then call mkdoc('myfile.Rnw') instead of pressing the compile button. After a few passes it generates myfile.pdf. Having this sort of thing built into RStudio would indeed be nicer. May 2 '14 at 17:57
• It might be a bit more robust to do Sys.setenv(RSTUDIO_PDFLATEX = Sys.which("latexmk")). Sep 16 '15 at 17:19

It is actually really easy to produce a PDF with knitr with LaTeX-code in RStudio with biblatex for citations.

You have to use the option bib_engine = "biber" from the package tinytex::latexmk within knitr::knit2pdf.

Just like here: knitr::knit2pdf(file.Rnw, bib_engine = "biber")

• This works for me, I wonder if there is a way to make make it permanent so you can use the RStudio render button Sep 9 '19 at 23:52

I think that the problem is in your backend, because Rstudio uses texi2dvi to write pdf and then it does not know about biber.

Try to change:

\usepackage[backend=biber]{biblatex}

with

\usepackage[backend=bibtex]{biblatex}

in the preamble.

Normally this work.

• That seems to work for the built in biblatex styles but unfortunately the APA package now requires biber, so that can't be made to work this way. May 2 '14 at 16:23

Even though the question was asked long ago, any reader in the future might find this useful:

http://texblog.org/2013/08/20/rknitr-automatic-bibliography-generation-with-biblatex-in-rstudio/

• This worked for me, and is the most clean solution I was looking for. <<Setup, eval=T, echo=FALSE, include = FALSE, results='hide'>>= setwd('myworkingdirectory') Sys.setenv(TEXINPUTS=getwd(), BIBINPUTS=getwd(), BSTINPUTS=getwd()) @  Mar 1 at 18:33

This kinda works when I press the compile button twice. It is just an ugly system call to biber.

\documentclass{article}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@misc{Doe,author={John Doe},title={Title}}
\end{filecontents}
\usepackage[backend=biber]{biblatex}
\begin{document}

Test \cite{Doe}

\printbibliography
\end{document}

<<biber>>=
system(paste("biber", sub("\\.Rnw$", "", current_input()))) @  • this is the best hack-fix that I got to work. Dec 15 '15 at 23:24 The standard procedure for getting citations to work properly is that you have to: 1) Run LaTeX 2) Run BibTex 3) Run LaTeX 4) Run LaTeX One option is to use the command texify, others use a makefile. I am not entirely sure about what knitr runs, but probably it does not run the sequence enough. Personally, I use Emacs with ESS, combined with AuCTeX; it really works well for me. P.S. I don't think you need to specify that it's a .bib file. It's an old question, which has no standard solution yet which I know of. (If I am wrong I would be pleased to be pointed to a better solution.) I got the following to work with rstudio, knitr, biblatex, and biber. It probably only works for linux, but could possibly be adapted to other systems. 1. create a wrapper file with the following content: #!/usr/bin/bash /usr/bin/latexmk -pv- -quiet -pdf -xelatex$@ 

Let's assume, you called the file ~/bin/rstudiolatex.sh. Make sure to use the correct path to bash which might be /bin/bash on your machine. The command line options to latexmk could be shortened I guess.

1. Make the file (~/bin/rstudiolatex) executable.

2. add the following line to the R startup ~/.Rprofile:

Sys.setenv(RSTUDIO_PDFLATEX = "/your/path/to/rstudiolatex.sh")

Make sure to insert your proper path to rstudiolatex.sh`.