added r data module

R/load_if_missing.R

@@ -0,0 +1,24 @@
+# Community Data Science Collective R Utilities
+#
+# Copyright (c) 2010-2016 Benjamin Mako Hill and Aaron Shaw 
+# mako@atdot.cc, aaronshaw@northwestern.edu
+
+# load a file if a variable is missing
+load.if.missing <- function (var.name, file.name) {
+  if (!exists(var.name)) {
+    load(file.name, parent.frame())
+
+    # check to see if we're dealing with a data.table because, if we
+    # are, we need to do some nasty back and forth
+    if (class(eval(as.name(var.name)))[1] == "data.table") {
+
+      # gnarly function that loads resorts things within the parent
+      # frame to get around the bug in data.table
+      assign(var.name,
+             data.table(as.data.frame(eval(as.name(var.name))),
+                        key=attr(eval(as.name(var.name)), "sorted")),
+             parent.frame())
+    }
+  }
+}
+