Improve internal column detection

For magpie objects, we can use the order of columns when determining which refer to the iso3c and year columns.
At the same time we need to check for an eventual second spatial dimension (fixes #22).

R/transform_user_input.R

@@ -4,7 +4,14 @@ transform_user_input <- function(gdp, unit_in, unit_out, source, use_USA_deflato
 
   # Convert to tibble, if necessary
   if (class(gdp)[1] == "magpie") {
-    gdp <- tibble::as_tibble(gdp) %>% dplyr::rename(tidyselect::any_of(c("iso3c" = "region")))
+    # Check if the magpie object has 2 spatial dimensions
+    spat2 <- all(grepl("\\.", magclass::getItems(gdp, dim = 1)))
+    gdp <- tibble::as_tibble(gdp)
+    if (!spat2) {
+      gdp <- gdp %>% dplyr::rename("iso3c" = 1, "year" = 2)
+    } else {
+      gdp <- gdp %>% dplyr::rename("iso3c" = 1, "spatial2" = 2, "year" = 3)
+    }
   }
 
   # Extract base years if they exist, and adjust string
@@ -118,7 +125,13 @@ transform_internal <- function(x, gdp, with_regions, require_year_column) {
 
   # Transform into original gdp type
   if (class(gdp)[1] == "magpie") {
-    x <- magclass::as.magpie(x, spatial = "iso3c", temporal = "year")
+    # Check if the original magpie object had 2 spatial dimensions
+    spat2 <- all(grepl("\\.", magclass::getItems(gdp, dim = 1)))
+    if (!spat2) {
+      x <- magclass::as.magpie(x, spatial = "iso3c", temporal = "year")
+    } else {
+      x <- magclass::as.magpie(x, spatial = c("iso3c", "spatial2"), temporal = "year")
+    }
     magclass::getSets(x) <- magclass::getSets(gdp)
     return(x)
   }