| packageDescription {utils} | R Documentation |
Parses and returns the ‘DESCRIPTION’ file of a package.
packageDescription(pkg, lib.loc = NULL, fields = NULL,
drop = TRUE, encoding = "")
packageVersion(pkg, lib.loc = NULL)
pkg |
a character string with the package name. |
lib.loc |
a character vector of directory names of R libraries,
or |
fields |
a character vector giving the tags of fields to return (if other fields occur in the file they are ignored). |
drop |
If |
encoding |
If there is an |
A package will not be ‘found’ unless it has a ‘DESCRIPTION’ file
which contains a valid Version field. Different warnings are
given when no package directory is found and when there is a suitable
directory but no valid ‘DESCRIPTION’ file.
An attached environment named to look like a package
(e.g. package:utils2) will be ignored.
packageVersion() is a convenience shortcut, allowing things
like if (packageVersion("MASS") < "7.3") { do.things } .
If a ‘DESCRIPTION’ file for the given package is found and can
successfully be read, packageDescription returns an object of
class "packageDescription", which is a named list with the
values of the (given) fields as elements and the tags as names, unless
drop = TRUE.
If parsing the ‘DESCRIPTION’ file was not successful, it returns
a named list of NAs with the field tags as names if fields
is not null, and NA otherwise.
packageVersion() returns a (length-one) object of class
"package_version".
packageDescription("stats")
packageDescription("stats", fields = c("Package", "Version"))
packageDescription("stats", fields = "Version")
packageDescription("stats", fields = "Version", drop = FALSE)
if(packageVersion("MASS") < "7.3")
message("you need to update 'MASS'")