R in a Nutshell, 2nd Edition

Getting Help

R includes a help system to help you get information about installed packages. To get help on a function, for example glm, you would type:

> help(glm)

or, equivalently:

> ?glm

To search for help on an operator, you need to place the operator in backquotes:

> ?`+`

If you’d like to try the examples in a help file, you can use the example function to automatically try them. For example, to see the example for glm, type:

> example(glm)

You can search for help on a topic, for example “regression,” using the help.search function:

> help.search("regression")

This can be very helpful if you can’t remember the name of a function; R will return a list of relevant topics. There is a shorthand for this command as well:

> ??regression

To get the help file for a package, you can sometimes use one of the commands above. However, you can also use the help option for the library command to get more complete information. For example, to get help on the grDevices library, you would use the following function:

> library(help="grDevices")

Some packages (especially packages from Bioconductor) include at least one vignette. A vignette is a short document that describes how to use the package, complete with examples. You can view a vignette using the vignette command. For example, to view the vignette for the affy package (assuming that you have installed this package), you would use the following command:

> vignette("affy")

To view available vignettes for all attached packages, you can use the following ...