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# Chunk Options

`opts_chunk` controls global chunk options, e.g.
`opts_chunk$set(tidy = FALSE)`, which can be overridden by local chunk
options. See all options at <http://yihui.name/knitr/options>; some
frequently used options:

eval
:   whether to evaluate the chunk

echo
:   whether to echo source code

results
:   `'markup'`, `'asis'`, `'hold'`, `'hide'`

tidy
:   whether to reformat R code

cache
:   whether to cache results

fig.width, fig.height, out.width, out.height
:   device and output size of figures

include
:   whether to include the chunk results in output

child
:   filenames of child documents

engine
:   language name (R, python, ...)


# Functions

`knit()`
:   the main function in this package; knit input document and write
    output

`purl()`
:   extract R code from an input document

`spin()`
:   spin goat's hair (an R script with roxygen comments) into wool (a
    literate programming document to be passed to `knit()`)

`stitch()`
:   insert an R script into a template and compile the document

`knit_hooks$set()`
:   set or reset chunk and output [hooks](http://yihui.name/knitr/hooks)

# Resources

-   homepage: <http://yihui.name/knitr>
-   development repository: <https://github.com/yihui/knitr>
    ([CRAN](http://cran.rstudio.com/package=knitr),
    [Rforge](http://rforge.net/knitr))
-   examples: <https://github.com/yihui/knitr-examples>
-   stackoverflow: <http://stackoverflow.com/questions/tagged/knitr>
-   mailing list: <https://groups.google.com/group/knitr>