For notebooks, R Markdown, and Rhtml, RStudio relies on Yihui Xie's knitr package for executing code chunks and merging the results. The knitr package can be installed via RStudio's Packages tab or with the command install.packages("knitr").
For LaTeX/Sweave files, the default is to use R's native Sweave driver. The knitr package is easier to use and has more options for fine-tuning, so in the rest of this chapter we assume that
knitr is always used. To make sure that knitr is also used for Sweave files, go to Tools | Options | Sweave and choose knitr as Weave Rnw files. If you're working in an RStudio project, you can set this as a project option as well by navigating to Project | Project Options | Sweave. When you work with LaTeX/Sweave, you need to have a working LaTeX distribution installed. Popular distributions are TeXLive for Linux, MikTeX for Windows, and MacTeX for Mac OS X.
