summary.cranly_dependence_tree: summary method for `cranly_dependence_tree` objects

Description

Hard dependence summaries for R packages from a cranly_dependence_tree object

Usage

# S3 method for cranly_dependence_tree
summary(object, ...)

Arguments

object

a cranly_dependence_tree object.

...

currently not used.

Value

A list with components n_generations, parents, and dependence_index.

Details

The summary method for a cranly_dependence_tree object returns the number of generations the R package(s) in the object inherit from (n_generations), the immediate parents of the R package(s) (parents), and a dependence index dependence_index defined as $$ -\frac{\sum_{i \in C_p; i \ne p} \frac{1}{N_i} g_i}{\sum_{i \in C_p; i \ne p} \frac{1}{N_i}} $$

where $C_p$ is the dependence tree for the package(s) $p$, $N_i$ is the total number of packages that depend, link or import package $i$, and $g_i$ is the generation that package $i$ appears in the dependence tree of package(s) $p$. The generation takes values on the non-positive integers, with the package(s) $p$ being placed at generation 0, the packages that $p$ links to, depends or imports at generation -1 and so on.

A dependence index of zero means that the $p$ only has immediate parents. The dependence index weights the dependencies based on how popular these are, in the sense that the index is not penalized if the package depends on popular packages. The greatest the dependence index is the more baggage the package carries, and the maintainers may want to remove any dependencies that are not necessary.

Examples

Run this code

# NOT RUN {
cran_db <- clean_CRAN_db()
package_network <- build_network(object = cran_db)

## Two light packages
dep_tree <- build_dependence_tree(package_network, package = "brglm")
summary(dep_tree)

dep_tree <- build_dependence_tree(package_network, package = "gnm")
summary(dep_tree)

## A somewhat heavier package (sorry)...
dep_tree <- build_dependence_tree(package_network, package = "cranly")
summary(dep_tree)

# }
# NOT RUN {
# }