Tecnico

R Reference Card
by Tom Short, EPRI PEAC, tshort@epri-peac.com 2004-11-07 Granted to the public domain. See www.Rpad.org for the source and latest version. Includes material from R for Beginners byEmmanuel Paradis (with permission).

Getting help
Most R functions have online documentation. help(topic) documentation on topic ?topic id. help.search("topic") search the help systemapropos("topic") the names of all objects in the search list matching the regular expression ”topic” help.start() start the HTML version of help str(a) display the internal *str*ucture of an R object summary(a)gives a “summary” of a, usually a statistical summary but it is generic meaning it has different operations for different classes of a ls() show objects in the search path; specify pat="pat" tosearch on a pattern ls.str() str() for each variable in the search path dir() show files in the current directory methods(a) shows S3 methods of a methods(class=class(a)) lists all the methods to handleobjects of class a

character or factor columns are surrounded by quotes ("); sep is the field separator; eol is the end-of-line separator; na is the string for missing values; use col.names=NA toadd a blank column header to get the column headers aligned correctly for spreadsheet input sink(file) output to file, until sink() Most of the I/O functions have a file argument. This can often be acharacter string naming a file or a connection. file="" means the standard input or output. Connections can include files, pipes, zipped files, and R variables. On windows, the file connection can also beused with description = "clipboard". To read a table copied from Excel, use x 3] all elements greater than 3 write.table(x,file="",row.names=TRUE,col.names=TRUE, x[x > 3 & x < 5] all elementsbetween 3 and 5 sep=" ") prints x after converting to a data frame; if quote is TRUE, x[x %in% c("a","and","the")] elements in the given set

Variable information
is.na(x), is.null(x), is.array(x),...