\Header{read.table}{Data Input}
\alias{read.csv}{read.table}
\alias{read.csv2}{read.table}
\alias{read.delim}{read.table}
\alias{read.delim2}{read.table}
\keyword{file}{read.table}
\keyword{connection}{read.table}
\begin{Description}\relax
Reads a file in table format and creates a data frame from it, with
cases corresponding to lines and variables to fields in the file.\end{Description}
\begin{Usage}
\begin{verbatim}
read.table(file, header = FALSE, sep = "", quote = "\"'", dec = ".",
           row.names, col.names, as.is = FALSE, na.strings = "NA",
           skip = 0, check.names = TRUE, fill = FALSE,
           strip.white = FALSE, blank.lines.skip = TRUE)

read.csv(file, header = TRUE, sep = ",", quote="\"", dec=".",
         fill = TRUE, ...)

read.csv2(file, header = TRUE, sep = ";", quote="\"", dec=",",
         fill = TRUE, ...)

read.delim(file, header = TRUE, sep = "\t", quote="\"", dec=".",
         fill = TRUE, ...)

read.delim2(file, header = TRUE, sep = "\t", quote="\"", dec=",",
         fill = TRUE, ...)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{file}] the name of the file which the data are to be read from.
Each row of the table appears as one line of the file.  If it does
not contain an \emph{absolute} path, the file name is
\emph{relative} to the current working directory,
\code{\Link{getwd}()}.

Alternatively, \code{file} can be a \code{\Link{connection}}, which
will be opened if necessary, and if so closed at the end of the
function call.  However, since the file must be read twice, this
will be resource-intensive except on seekable connections.

\item[\code{header}] a logical value indicating whether the file contains the
names of the variables as its first line.  If missing, the value is
determined from the file format: \code{header} is set to \code{TRUE}
if and only if the first row contains one fewer field than the
second.
\item[\code{sep}] the field separator character.  Values on each line of the
file are separated by this character.  If \code{sep = ""} the
separator is ``white space'', that is one or more spaces, tabs or
newlines.
\item[\code{quote}] the set of quoting characters. To disable quoting
altogether, use \code{quote=""}.  See \code{\Link{scan}} for the
behaviour on quotes embedded in quotes.
\item[\code{dec}] the character used in the file for decimal points.
\item[\code{row.names}] a vector of row names.  This can be a vector giving
the actual row names, or a single number giving the column of the
table which contains the row names, or character string giving the
name of the table column containing the row names.
\item[\code{col.names}] a vector of optional names for the variables.
The default is to use \code{"V"} followed by the column number.
\item[\code{as.is}] the default behavior of \code{read.table} is to convert
non-numeric variables to factors.  The variable \code{as.is}
controls this conversion.  Its value is either a vector of logicals
(values are recycled if necessary), or a vector of numeric indices
which specify which columns should be left as character strings.
\item[\code{na.strings}] a vector strings which are to be interpreted as
\code{\Link{NA}} values.
\item[\code{skip}] the number of lines of the data file to skip before
beginning to read data.
\item[\code{check.names}] logical.  If \code{TRUE} then the names of the
variables in the data frame are checked to ensure that they are
syntactically valid variable names.  If necessary they are adjusted
(by \code{\Link{make.names}}) so that they are.
\item[\code{fill}] logical. If \code{TRUE} then in case the rows have unequal
length, blank fields are implicitly added.
\item[\code{strip.white}] logical. Used only when \code{sep} has
been specified, and allows the stripping of leading and trailing
white space from \code{character} fields (\code{numeric} fields
are always stripped).  See \code{\Link{scan}} for further details,
remembering that the columns may include the row names.
\item[\code{blank.lines.skip}] logical: if \code{TRUE} blank lines in the
input are ignored.
\item[\code{...}] Further arguments to \code{read.table}.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
If \code{row.names} is not specified and the header line has one less
entry than the number of columns, the first column is taken to be the
row names.  This allows data frames to be read in from the format in
which they are printed.

\code{read.csv} and \code{read.csv2} are identical to
\code{read.table} except for the defaults.  They are intended for
reading ``comma separated value'' files (\file{.csv}) or the variant
used in countries that use a comma as decimal point and a semicolon
as field separator.  Similarly, \code{read.delim} and
\code{read.delim2} are for reading delimited files, defaulting to the
TAB character for the delimiter.  Notice that \code{header = TRUE} and
\code{fill = TRUE} in these variants.\end{Details}
\begin{Value}
A data frame (\code{\Link{data.frame}}) containing a representation of
the data in the file.

This function is the principal means of reading tabular data into \R.\end{Value}
\begin{Note}\relax
The implementation of \code{read.table} currently reads everything as
character using \code{\Link{scan}} and subsequently defines
\code{"numeric"} or \code{\Link{factor}} variables.

This is quite memory consuming for files of thousands of records and
may need larger memory, see \code{\Link{Memory}}.\end{Note}
\begin{SeeAlso}\relax
The `R Data Import/Export' manual.

\code{\Link{scan}},
\code{\Link{read.fwf}} for reading \emph{f}ixed \emph{w}idth
\emph{f}ormatted input;
\code{\Link{read.table.url}} for ``reading'' data from the internet;
\code{\Link{write.table}};
\code{\Link{data.frame}}.\end{SeeAlso}

