data {utils} | R Documentation |
Loads specified data sets, or list the available data sets.
data(..., list = character(0), package = NULL, lib.loc = NULL,
verbose = getOption("verbose"), envir = .GlobalEnv)
... |
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 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 |
verbose |
a logical. If |
envir |
the environment where the data should be loaded. |
Currently, four formats of data files are supported:
files ending ‘.R’ or ‘.r’ are
source()
d in, with the R working directory changed
temporarily to the directory containing the respective file.
(data
ensures that the utils package is attached, in
case it had been run via utils::data
.)
files ending ‘.RData’ or ‘.rda’ are
load()
ed.
files ending ‘.tab’, ‘.txt’ or ‘.TXT’ are read
using read.table(..., header = TRUE)
, and hence
result in a data frame.
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).
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.
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.
help
for obtaining documentation on data sets,
save
for creating the second (‘.rda’) kind
of data, typically the most efficient one.
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'