dcf {base} | R Documentation |
Reads or writes an R object from/to a file in Debian Control File format.
read.dcf(file, fields=NULL) write.dcf(x, file = "", append = FALSE, indent = 0.1 * getOption("width"), width = 0.9 * getOption("width"))
file |
either a character string naming a file or a connection.
"" indicates output to the console. For read.dcf this
can name a gzip -compressed file. |
fields |
Fields to read from the DCF file. Default is to read all fields. |
x |
the object to be written, typically a data frame. If not, it
is attempted to coerce x to a data frame. |
append |
logical. If TRUE , the output is appended to the
file. If FALSE , any existing file of the name is destroyed. |
indent |
a positive integer specifying the indentation for continuation lines in output entries. |
width |
a positive integer giving the target column for wrapping lines in the output. |
DCF is a simple format for storing databases in plain text files that can easily be directly read and written by humans. DCF is used in various places to store R system information, like descriptions and contents of packages.
The DCF rules as implemented in R are:
tag:value
, i.e.,
have a name tag and a value for the field, separated
by :
(only the first :
counts). The value can be
empty (=whitespace only).
read.dcf
returns a character matrix with one line per record
and one column per field. Leading and trailing whitespace of field
values is ignored. If a tag name is specified, but the corresponding
value is empty, then an empty string of length 0 is returned. If the
tag name of a fields is never used in a record, then NA
is
returned. If there are multiple records with the same tag name, the
last one encountered is returned.
## Create a reduced version of the 'CONTENTS' file in package 'splines' x <- read.dcf(file = system.file("CONTENTS", package = "splines"), fields = c("Entry", "Description")) write.dcf(x)