Better handling of subset= in mlearning()

Author: phgrosjean

R/mlearning.R

@@ -123,9 +123,15 @@
 mlearning <- function(formula, data, method, model.args, call = match.call(),
 ..., subset, na.action = na.fail) {
   # Our own construction of response vector and terms matrix
-  if (missing(model.args))
-    model.args <- list(formula  = formula, data = substitute(data),
-      subset = substitute(subset))
+  if (missing(model.args)) {
+    if (missing(subset) || is.null(subset) || !length(subset) ||
+        as.character(subset) == "") {
+      model.args <- list(formula  = formula, data = substitute(data))
+    } else {
+      model.args <- list(formula  = formula, data = substitute(data),
+        subset = substitute(subset))
+    }
+  }
 
   # Get data and initial number of cases
   if (missing(data)) {