033-file-extension.Rnw

\documentclass{article}

\begin{document}

We want the file extension when including a figure into LaTeX.

<<setup>>=
library(knitr)
hook_plot = knit_hooks$get('plot')
knit_hooks$set(plot = function(x, options) {
   # if x is foo.pdf, make it foo.pdf.whatever so the plot hook removes the extension internally
  x = paste(c(x, 'whatever'), collapse = '.')
  hook_plot(x, options)
})
@

You should see \textbackslash{}includegraphics\{test.pdf\} instead of \textbackslash{}includegraphics\{test\}.

<<test-a>>=
# pdf figure
plot(1)
@

<<test-b, dev='png'>>=
# png figure
plot(2)
@

\end{document}