dcf

R Base 3.6.2

Reads or writes an R object from/to a file in Debian Control File format.

Syntax

read.dcf(file, fields = NULL, all = FALSE, keep.white = NULL)<p></p><p>write.dcf(x, file = "", append = FALSE, useBytes = FALSE,
          indent = 0.1 * getOption("width"),
          width = 0.9 * getOption("width"),
          keep.white = NULL)</p>

Arguments

Parameter	Description
`file`	either a character string naming a file or a connection. "" indicates output to the console. For read.dcf this can name a compressed file (see gzfile).
`fields`	Fields to read from the DCF file. Default is to read all fields.
`all`	a logical indicating whether in case of multiple occurrences of a field in a record, all these should be gathered. If all is false (default), only the last such occurrence is used.
`keep.white`	a character string with the names of the fields for which whitespace should be kept as is, or NULL (default) indicating that there are no such fields. Coerced to character if possible. For fields where whitespace is not to be kept as is, read.dcf removes leading and trailing whitespace, and write.dcf folds using strwrap.
`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.
`useBytes`	logical to be passed to writeLines(), see there: “for expert use”.
`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.

Return Value

The default read.dcf(all = FALSE) returns a character matrix with one row per record and one column per field. Leading and trailing whitespace of field values is ignored unless a field is listed in keep.white. If a tag name is specified in the file, but the corresponding value is empty, then an empty string is returned. If the tag name of a field is specified in fields but never used in a record, then the corresponding value is NA. If fields are repeated within a record, the last one encountered

Details

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: A database consists of one or more records, each with one or more named fields. Not every record must contain each field. Fields may appear more than once in a record. Regular lines start with a non-whitespace character. Regular lines are of form 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 (i.e., whitespace only). Lines starting with whitespace are continuation lines (to the preceding field) if at least one character in the line is non-whitespace. Co

Examples

Example

# NOT RUN {
## Create a reduced version of the DESCRIPTION file in package 'splines'
x <- read.dcf(file = system.file("DESCRIPTION", package = "splines"),
              fields = c("Package", "Version", "Title"))
write.dcf(x)

## An online DCF file with multiple records
con <- url("http://cran.r-project.org/src/contrib/PACKAGES")
y <- read.dcf(con, all = TRUE)
close(con)
utils::str(y)
# }

dcf

Syntax

Arguments

Return Value

Details

Examples

See Also