transitive dependencies in R

transitive_dependencies.R

# modified slightly from https://gist.github.com/floybix/6533090

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 <- pkg
    it <- 1
    while (it <= length(deps)) {
      this <- deps[it]
      deps <- c(deps, dependencies(this, pl = pl))
      deps <- unique(deps)
      it <- it + 1
    }
    deps
  }