Data Sets

Description

Loads specified data sets, or list the available data sets.

Usage

data(..., list = character(0), package = .packages(),
     lib.loc = NULL, verbose = getOption("verbose"),
     envir = .GlobalEnv)

Arguments

Details

Currently, four formats of data files are supported:

1. files ending ‘.R’ or ‘.r’ are source()d in, with the R working directory changed temporarily to the directory containing the respective file.
2. files ending ‘.RData’ or ‘.rda’ are load()ed.
3. files ending ‘.tab’, ‘.txt’ or ‘.TXT’ are read using read.table(..., header = TRUE), and hence result in a data frame.
4. files ending ‘.csv’ or ‘.CSV’ are read using read.table(..., header = TRUE, sep = ";"), and also result in a data frame.

If more than one matching file name is found, the first on this list is used.

The data sets to be loaded can be specified as a sequence of names or character strings, or as the character vector list, or as both.

For each given data set, the first two types (‘.R’ or ‘.r’, and ‘.RData’ or ‘.rda’ files) can create several variables in the load environment, which might all be named differently from the data set. The second two (‘.tab’, ‘.txt’, or ‘.TXT’, and ‘.csv’ or ‘.CSV’ files) will always result in the creation of a single variable with the same name as the data set.

If no data sets are specified, data lists the available data sets. It looks for a new-style data index in the ‘Meta’ or, if this is not found, an old-style ‘00Index’ file in the ‘data’ directory of each specified package, and uses these files to prepare a listing. If there is a ‘data’ area but no index, available data files for loading are computed and included in the listing, and a warning is given: such packages are incomplete. The information about available data sets is returned in an object of class "packageIQR". The structure of this class is experimental. In earlier versions of R, an empty character vector was returned along with listing available data sets.

If lib.loc is not specified, the data sets are searched for amongst those packages already loaded, followed by the ‘data’ directory (if any) of the current working directory and then packages in the specified libraries. If lib.loc is specified, packages are searched for in the specified libraries, even if they are already loaded from another library.

To just look in the ‘data’ directory of the current working directory, set package = NULL.

Value

a character vector of all data sets specified, or information about all available data sets in an object of class "packageIQR" if none were specified.

Note

The data files can be many small files. On some file systems it is desirable to save space, and the files in the ‘data’ directory of an installed package can be zipped up as a zip archive ‘Rdata.zip’. You will need to provide a single-column file ‘filelist’ of file names in that directory.

One can take advantage of the search order and the fact that a ‘.R’ file will change directory. If raw data are stored in ‘mydata.txt’ then one can set up ‘mydata.R’ to read ‘mydata.txt’ and pre-process it, e.g., using transform. For instance one can convert numeric vectors to factors with the appropriate labels. Thus, the ‘.R’ file can effectively contain a metadata specification for the plaintext formats.

See Also

help for obtaining documentation on data sets, save for creating the second (‘.rda’) kind of data, typically the most efficient one.

Examples

require(utils)
data()                      # list all available data sets
data(package = "base")      # list the data sets in the base package
data(USArrests, "VADeaths") # load the data sets 'USArrests' and 'VADeaths'
help(USArrests)             # give information on data set 'USArrests'