Extract ggplot2-extension components from a CRAN package

Downloads a CRAN source tarball for pkg_name (unless cached), extracts the package NAMESPACE, and calls analyze_pkg_source() to identify exported ggplot2 “grammar” components (e.g., functions named like geom_*, stat_*, scale_*, etc., depending on what analyze_pkg_source() detects).

Usage

get_components_cran(pkg_name, cran_db = NULL, cache_root = "~/CRAN")

Arguments

pkg_name

Character scalar. CRAN package name.

cran_db

Optional CRAN package database as returned by tools::CRAN_package_db(). If NULL, it is computed on demand.

cache_root

Character scalar. Root directory used for on-disk caching of extracted NAMESPACE files. Default is "~/CRAN".

Value

A data.frame with columns:

package

Package name.

component

Component type/category identified by analyze_pkg_source().

fname

Function name.

If the package cannot be found on CRAN, downloaded, or its NAMESPACE cannot be extracted, returns an empty data frame with the same columns.

Details

The function caches the NAMESPACE file at cache_root/<pkg>/<version>/NAMESPACE and keeps that directory “clean” by removing any other files that might be present.

Network access is required on the first run for a given package version. The cache is keyed by package version from cran_db, so updates on CRAN will be cached separately.

This function assumes analyze_pkg_source(pkg_name, cache_dir) exists and can operate given a directory that contains (at minimum) a NAMESPACE file.

See also

tools::CRAN_package_db(), utils::download.file(), utils::untar()

Examples

if (FALSE) { # \dontrun{
# Using a precomputed CRAN DB speeds up repeated calls
db <- tools::CRAN_package_db()
out <- get_components_cran("ggrepel", cran_db = db, cache_root = tempdir())
head(out)

# Use the default cache under ~/CRAN
out2 <- get_components_cran("ggridges")
} # }