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, 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, ...)

### 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()`. Alternatively, `file` can be a `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.
`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: `header` is set to `TRUE` if and only if the first row contains one fewer field than the second.
`sep` | the field separator character. Values on each line of the file are separated by this character. If `sep = ""` the separator is ``white space'', that is one or more spaces, tabs or newlines.
`quote` | the set of quoting characters. To disable quoting altogether, use `quote=""`. See `scan` for the behaviour on quotes embedded in quotes.
`dec` | the character used in the file 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 syntactically valid variable names. If necessary they are adjusted (by `make.names`) so that they are.
`fill` | logical. If `TRUE` then in case the rows have unequal length, blank fields are implicitly added.
`strip.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.
`blank.lines.skip` | logical: if `TRUE` blank lines in the input are ignored.
`...` | Further arguments to `read.table`.

### Details

If `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.

`read.csv` and `read.csv2` are identical to `read.table` except for the defaults. They are intended for reading ``comma separated value'' files (``.csv`') or the variant used in countries that use a comma as decimal point and a semicolon as field separator. Similarly, `read.delim` and `read.delim2` are for reading delimited files, defaulting to the TAB character for the delimiter. Notice that `header = TRUE` and `fill = 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`.

### See Also

The `R Data Import/Export' manual.

`scan`, `read.fwf` for reading fixed width formatted input; `read.table.url` for ``reading'' data from the internet; `write.table`; `data.frame`.