R: Data Input

read.table {base}

R Documentation

Data Input

Description

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.

Usage

read.table(file, header = FALSE, sep = "", quote = "\"'", dec = ".",
           row.names, col.names, as.is = FALSE, na.strings = "NA",
           skip = 0, check.names = TRUE, strip.white = FALSE)

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

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

Arguments

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 absolute path, the file name is relative to the current working directory, getwd().

a logical value indicating whether the file contains the names of the variables as its first line.

sep

the field separator character. Values on each line of the file are separated by this character.

quote

the set of quoting characters. To disable quoting altogether, use quote="".

dec

the character used in the fike for decimal points.

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.

col.names

a vector of optional names for the variables. The default is to use "V" followed by the column number.

as.is

the default behavior of read.table is to convert non-numeric variables to factors. The variable 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.

na.strings

a vector strings which are to be interpreted as NA values.

skip

the number of lines of the data file to skip before beginning to read data.

check.names

logical. If TRUE then the names of the variables in the data frame are checked to ensure that they are valid variable names. If necessary they are adjusted (by make.names) so that they are.

skip.white

logical. Used only when sep has been specified, and allows the stripping of leading and trailing white space from character fields (numeric fields are always stripped). See scan for further details, remembering that the columns may include the row names.

...

Further arguments to read.table.

Details

read.csv and read.csv2 are identical to read.table except for the defaults. They are intended for reading "comma separated variable" files (.csv) or the variant used in countries that use comma as decimal point and consequently semicolon as field separator. Notice that header=TRUE in these variants.

Value

A data frame (data.frame) containing a representation of the data in the file.

This function is the principal means of reading tabular data into R.

Note

The implementation of read.table currently reads everything as character using scan and subsequently defines "numeric" or factor variables.

This is quite memory consuming for files of thousands of records and may need larger memory, see Memory.