テキストファイルの読み出しについては，read.table() と scan() の2つを紹介しておきます．
read.table(file, header = FALSE, sep = "", quote = "\"'",
dec = ".", row.names, col.names,
as.is = !stringsAsFactors,
na.strings = "NA", colClasses = NA, nrows = -1,
skip = 0, check.names = TRUE, fill = !blank.lines.skip,
strip.white = FALSE, blank.lines.skip = TRUE,
comment.char = "#",
allowEscapes = FALSE, flush = FALSE,
stringsAsFactors = default.stringsAsFactors(),
encoding = "unknown")
- 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(). Tilde-expansion is performed where supported.
Alternatively, file can be a readable text-mode connection (which will
be opened for reading if necessary, and if so closed (and hence
destroyed) at the end of the function call). (If stdin() is used, the
prompts for lines may be somewhat confusing. Terminate input with a
blank line or an EOF signal, Ctrl-D on Unix and Ctrl-Z on Windows. Any
pushback on stdin() will be cleared before return.)
file can also be a complete URL.
To read a data file not in the current encoding (for example a Latin-1
file in a UTF-8 locale or conversely) use a file connection setting the
- 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 number of columns.
- sep the field separator character. Values on each line of the file are
separated by this character. If sep = "" (the default for read.table)
the separator is ‘white space’, that is one or more spaces, tabs,
newlines or carriage returns.
- quote the set of quoting characters. To disable quoting altogether, use
quote = "". See scan for the behaviour on quotes embedded in quotes.
Quoting is only considered for columns read as character, which is all
of them unless colClasses is specified.
- 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.
If there is a header and the first row contains one fewer field than the
number of columns, the first column in the input is used for the row
names. Otherwise if row.names is missing, the rows are numbered.
Using row.names = NULL forces row numbering. Missing or NULL row.names
generate row names that are considered to be ‘automatic’ (and not
preserved by as.matrix).
- 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 character
variables (which are not converted to logical, numeric or complex) to
factors. The variable as.is controls the conversion of columns not
otherwise specified by colClasses. Its value is either a vector of
logicals (values are recycled if necessary), or a vector of numeric or
character indices which specify which columns should not be converted to
Note: to suppress all conversions including those of numeric columns,
set colClasses = "character".
Note that as.is is specified per column (not per variable) and so
includes the column of row names (if any) and any columns to be skipped.
- na.strings a character vector of strings which are to be interpreted as
NA values. Blank fields are also considered to be missing values in
logical, integer, numeric and complex fields.
- colClasses character. A vector of classes to be assumed for the columns.
Recycled as necessary, or if the character vector is named, unspecified
values are taken to be NA.
Possible values are NA (when type.convert is used), "NULL" (when the
column is skipped), one of the atomic vector classes (logical, integer,
numeric, complex, character, raw), or "factor", "Date" or "POSIXct".
Otherwise there needs to be an as method (from package methods) for
conversion from "character" to the specified formal class.
Note that colClasses is specified per column (not per variable) and so
includes the column of row names (if any).
- nrows integer: the maximum number of rows to read in. Negative and other
invalid values are ignored.
- skip integer: 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,
and also to ensure that there are no duplicates.
- fill logical. If TRUE then in case the rows have unequal length, blank
fields are implicitly added. See ‘Details’.
- 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.
- comment.char character: a character vector of length one containing a
single character or an empty string. Use "" to turn off the
interpretation of comments altogether.
- allowEscapes logical. Should C-style escapes such as \n be processed or
read verbatim (the default)? Note that if not within quotes these could
be interpreted as a delimiter (but not as a comment character). For more
details see scan.
- flush logical: if TRUE, scan will flush to the end of the line after
reading the last of the fields requested. This allows putting comments
after the last field.
- stringsAsFactors logical: should character vectors be converted to
factors? Note that this is overridden bu as.is and colClasses, both of
which allow finer control.
- encoding encoding to be assumed for input strings. It is used to mark
character strings as known to be in Latin-1 or UTF-8: it is not used to
re-encode the input. For an example of how to do so, see the examples
- ... Further arguments to be passed to read.table.
Chambers, J. M. (1992) Data for models. Chapter 3 of Statistical Models
in S eds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole.