floybix · September 12, 2013 04:32 · Sep 12, 2013
diff --git a/transitive_dependencies.r b/transitive_dependencies.r
@@ -0,0 +1,28 @@
+## 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)
+}