fix rosetta indexing

closes #1110

Author: jgabry

rstan/rstan/R/lookup.R

@@ -27,14 +27,16 @@ lookup <- function(FUN, ReturnType = character()) {
   if(is.function(FUN)) FUN <- deparse(substitute(FUN))
   if(!is.character(FUN)) stop("'FUN' must be a character string for a function")
   if(length(FUN) != 1) stop("'FUN' must be of length one")
-  
+
   if(FUN == "nrow") FUN <- "NROW"
   if(FUN == "ncol") FUN <- "NCOL"
+
+  keep_cols <- !(colnames(rosetta) == "RFunction")
   if(exists(FUN)) {
     matches <- as.logical(charmatch(rosetta$RFunction, FUN, nomatch = 0L))
-    if(any(matches)) return(rosetta[matches,-1,drop=FALSE])
+    if(any(matches)) return(rosetta[matches, keep_cols, drop = FALSE])
   }
   matches <- grepl(FUN, rosetta$StanFunction, ignore.case = TRUE)
-  if(any(matches)) return(rosetta[matches,-1,drop=FALSE])
+  if(any(matches)) return(rosetta[matches, keep_cols, drop = FALSE])
   else return("no matching Stan functions")
 }