Subfigures or Subcaptions with knitr?

Question

Is it possible to produce subfigures (with associated subcaptions) using knitr? Here is a minimal working example:

\documentclass{article}  \begin{document}  <<echo = FALSE, fig.cap = c("Some numbers.", "Some more numbers."), out.width = "0.5\\textwidth", fig.align = "center">>=  plot(1:10) plot(30:100)  @  \end{document} 

This results in two figures labelled Figure 1 and Figure 2 with captions as defined (respectively). But I want them to be labelled "Figure 1a" and "Figure 1b", as you can do with the subcaption LaTeX package.

I know there is a knitr options "fig.env", but this doesn't solve it (at least not using, for example, "fig.env = 'subfigure'"). There is a similar post here regarding Sweave, but the solution is an inelegant hack: http://texblog.org/2011/12/01/sweave-subfig-controlling-figure-size-and-placement/

Answer 1

knitr (>= v1.5) supports subfigures. You can use the chunk option fig.subcap. Here is a minimal example.

\documentclass{article} \usepackage{subfig} \begin{document}  <<fig-sub, fig.cap='two plots', fig.subcap=c('one plot', 'the other one'), out.width='.49\\linewidth'>>= plot(1:10) plot(rnorm(10), pch=19) @  \end{document}