R notes

Installing and using libraries

Packages are installed from a CRAN repository to a local library directory. The default users library must be created at ~/R/x86_64-pc-linux-gnu-library/{version#}, but packages can also be installed to /usr/local/lib/R/site-library if permissions allow.

Install packages using:

install.packages(c('nlme', 'lattice', 'knitr', 'ggplot2'))

This will prompt the user to select a CRAN mirror (and make a user library if it is not already there).

Packages can then be loaded from a library with:

library('ggplot2')

Sometimes the core R packages on Debian go out of date and need to be updated. Start R with sudo and run:

update.packages()

For other, user-installed R packages, run update.packages('{packagename}').

knitr

Knitr allows literate programming with R - i.e. R code is written into latex, markdown, or other text markup formats. Running knitr will then convert the document by processing the markup, running the R code, and embedding all the output into a PDF, HTML, or document. This functionality is accessible from Rstudio also.

It's easiest (for me) to use knitr with markdown. This means creating file.Rmd and embedding code in "chunks" that look like:

```{r}
  plot(y ~ x)
```

There are a number of options that can be put in the braces at the start of the chunk to influence how the code is run and incorporated into the output of the file. The resulting .Rmd file can be converted (from within R), by running knit2html:

library(knitr)
knit2html(file.Rmd)

Stitch

Stitch is knitr's most basic way to output results from an R script:

library('knitr')
stitch_rhtml('scriptname.r')

This outputs an .html file that embeds all code and output (plots, tables, objects, etc) in the document. Nicely viewable in a browser. stitch can also do latex, but its not working for me yet.

Resources