write.table
Data Output
write.table
prints its required argument x
(after
converting it to a data frame if it is not one nor a matrix) to
a file or connection.
Usage
write.table(x, file = "", append = FALSE, quote = TRUE, sep = " ",
eol = "
", na = "NA", dec = ".", row.names = TRUE,
col.names = TRUE, qmethod = c("escape", "double"),
fileEncoding = "")write.csv(...)
write.csv2(...)
Arguments
- x
- the object to be written, preferably a matrix or data frame.
If not, it is attempted to coerce
x
to a data frame. - file
- either a character string naming a file or a connection
open for writing.
""
indicates output to the console. - append
- logical. Only relevant if
file
is a character string. IfTRUE
, the output is appended to the file. IfFALSE
, any existing file of the name is destroyed. - quote
- a logical value (
TRUE
orFALSE
) or a numeric vector. IfTRUE
, any character or factor columns will be surrounded by double quotes. If a numeric vector, its elements are taken as the indices of columns to quote. In both cases, row and column names are quoted if they are written. IfFALSE
, nothing is quoted. - sep
- the field separator string. Values within each row of
x
are separated by this string. - eol
- the character(s) to print at the end of each line (row).
For example,
eol = "\r "
will produce Windows' line endings on a Unix-alike OS, andeol = "\r"
will produce files as expected by Excel:mac 2004. - na
- the string to use for missing values in the data.
- dec
- the string to use for decimal points in numeric or complex columns: must be a single character.
- row.names
- either a logical value indicating whether the row
names of
x
are to be written along withx
, or a character vector of row names to be written. - col.names
- either a logical value indicating whether the column
names of
x
are to be written along withx
, or a character vector of column names to be written. See the section onCSV files for the meaning ofcol.names = NA
. - qmethod
- a character string specifying how to deal with embedded
double quote characters when quoting strings. Must be one of
"escape"
(default forwrite.table
), in which case the quote character is escaped in C style by a backslash, or"double"
(default forwrite.csv
andwrite.csv2
), in which case it is doubled. You can specify just the initial letter. - fileEncoding
- character string: if non-empty declares the
encoding to be used on a file (not a connection) so the character data can
be re-encoded as they are written. See
file
. - ...
- arguments to
write.table
:append
,col.names
,sep
,dec
andqmethod
cannot be altered.
Details
If the table has no columns the rownames will be written only if
row.names = TRUE
, and vice versa.
Real and complex numbers are written to the maximal possible precision.
If a data frame has matrix-like columns these will be converted to
multiple columns in the result (via as.matrix
)
and so a character col.names
or a numeric quote
should
refer to the columns in the result, not the input. Such matrix-like
columns are unquoted by default.
Any columns in a data frame which are lists or have a class
(e.g., dates) will be converted by the appropriate as.character
method: such columns are unquoted by default. On the other hand,
any class information for a matrix is discarded and non-atomic
(e.g., list) matrices are coerced to character.
Only columns which have been converted to character will be quoted if
specified by quote
.
The dec
argument only applies to columns that are not subject
to conversion to character because they have a class or are part of a
matrix-like column (or matrix), in particular to columns protected by
I()
. Use options("OutDec")
to control
such conversions.
In almost all cases the conversion of numeric quantities is governed
by the option "scipen"
(see options
), but with
the internal equivalent of digits = 15
. For finer control, use
format
to make a character matrix/data frame, and call
write.table
on that.
These functions check for a user interrupt every 1000 lines of output.
If file
is a non-open connection, an attempt is made to open it
and then close it after use.
To write a Unix-style file on Windows, use a binary connection
e.g.file = file("filename", "wb")
.
Note
write.table
can be slow for data frames with large numbers
(hundreds or more) of columns: this is inevitable as each column could
be of a different class and so must be handled separately. If they
are all of the same class, consider using a matrix instead.
CSV files
By default there is no column name for a column of row names. If
These wrappers are deliberately inflexible: they are designed to
ensure that the correct conventions are used to write a valid file.
Attempts to change CSV files do not record an encoding, and this causes problems if they
are not ASCII for many other applications. Windows Excel 2007/10 will
open files (e.g., by the file association mechanism) correctly if they
are ASCII or UTF-16 (use There is an IETF RFC4180 (col.names = NA
and row.names = TRUE
a blank column name
is added, which is the convention used for CSV files to be read by
spreadsheets. Note that such CSV files can be read in Rby
read.csv(file = "write.csv
and write.csv2
provide convenience wrappers
for writing CSV files. They set sep
and dec
(see
below), qmethod = "double"
, and col.names
to NA
if row.names = TRUE
(the default) and to TRUE
otherwise.write.csv
uses "."
for the decimal point and a comma for
the separator.write.csv2
uses a comma for the decimal point and a semicolon for
the separator, the Excel convention for CSV files in some Western
European locales.append
, col.names
, sep
,
dec
or qmethod
are ignored, with a warning.fileEncoding = "UTF-16LE"
) or perhaps
in the current Windows codepage (e.g., "CP1252"
), but the
write.csv
writes compliant files on Windows: use
eol = "\r
"
on other platforms.
See Also
The
write.matrix
in package
Examples
library(utils)
## To write a CSV file for input to Excel one might use
x <- data.frame(a = I("a \" quote"), b = pi)
write.table(x, file = "foo.csv", sep = ",", col.names = NA,
qmethod = "double")
## and to read this file back into R one needs
read.table("foo.csv", header = TRUE, sep = ",", row.names = 1)
## NB: you do need to specify a separator if qmethod = "double".
### Alternatively
write.csv(x, file = "foo.csv")
read.csv("foo.csv", row.names = 1)
## or without row names
write.csv(x, file = "foo.csv", row.names = FALSE)
read.csv("foo.csv")
## To write a file in Mac Roman for simple use in Mac Excel 2004/8
write.csv(x, file = "foo.csv", fileEncoding = "macroman")
## or for Windows Excel 2007/10
write.csv(x, file = "foo.csv", fileEncoding = "UTF-16LE")