data {utils} | R Documentation

## Data Sets

### Description

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

### Usage

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

### Arguments

`...` | a sequence of names or literal character strings.
`list` | a character vector.
`package` | a character vector giving the package(s) to look in for data sets, or `NULL`. By default, all packages in the search path are used, then the ‘`data`’ subdirectory (if present) of the current working directory.
`lib.loc` | a character vector of directory names of R libraries, or `NULL`. The default value of `NULL` corresponds to all libraries currently known.
`verbose` | a logical. If `TRUE`, additional diagnostics are printed.
`envir` | the environment where the data should be loaded.

### 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. Where the datasets have a different name from the argument that should be used to retrieve them the index will have an entry like `beaver1 (beavers)` which tells us that dataset `beaver1` can be retrieved by the call `data(beaver)`.

If `lib.loc` and `package` are both `NULL` (the default), the data sets are searched for in all the currently loaded packages then in the ‘`data`’ directory (if any) of the current working directory.

If `lib.loc = NULL` but `package` is specified as a character vector, the specified package(s) are searched for first amongst loaded packages and then in the default library/ies (see `.libPaths`).

If `lib.loc` is specified (and not `NULL`), packages are searched for in the specified library/ies, even if they are already loaded from another library.

To just look in the ‘`data`’ directory of the current working directory, set `package = character(0)` (and `lib.loc = NULL`, the default).

### 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
    try(data(package = "rpart") )# list the data sets in the rpart package
    data(USArrests, "VADeaths")  # load the data sets 'USArrests' and 'VADeaths'
    help(USArrests)              # give information on data set 'USArrests'

[Package utils version 2.3.1 Index]