Extending Markdown with R Markdown

As mentioned earlier, R Markdown extends Markdown. It offers many features to enhance it. There are various examples in R Markdown's documentation (http://rmarkdown.rstudio.com/gallery.html) where you may get a sense of what's possible. In this section, we will focus on code chunks, tables, graphs, local and global chunk options, and caching.

Code chunks

Code chunks are simply standard Markdown code blocks, which have a special syntax that uses curly braces ({}) along the top line of the block to send metadata to knitr, about how the block should be treated. The metadata sent is in the form of parameters with the key = value format. We'll cover more on this in the Chunk options section.

When you use a block header like (```{r chunk-label}), knitr knows that it's an R code block which will be identified with the chunk-label label. The chunk label is not a requirement, and if you do not specify one, one will be automatically created for you, but they are useful...