Find all transitive dependencies of an R package.

transitive_dependencies.r

## find all transitive dependencies of an R package.

distrib.pkgs <- library(lib.loc=R.home("library"))$results[,1]

dependencies <-
  function(pkg, dependencies = c("Depends", "Imports", "LinkingTo"),
           pl = installed.packages())
{
  if (!(pkg %in% rownames(pl))) stop("unknown pkg " pkg)
  fields <- pl[pkg, dependencies]
  fields <- fields[!is.na(fields)]
  deps <- unlist(strsplit(fields, ", "))
  deps <- sub(" \\(.*\\)", "", deps)
  setdiff(deps, c("R", distrib.pkgs))
}

transitive_dependencies <-
  function(pkg, pl = installed.packages())
{
  deps <- c()
  more <- pkg
  while (length(more) > 0) {
    this <- head(more, 1)
    deps <- c(deps, dependencies(this, pl = pl))
    more <- tail(more, -1)
  }
  unique(deps)
}