lib/eps/label_encoder.rb in eps-0.3.0 vs lib/eps/label_encoder.rb in eps-0.3.1

@@ -22,12 +22,16 @@
     def transform(y)
       y.map do |yi|
         if yi.nil?
           nil
         else
-          v = @labels[yi.to_s]
-          raise "Unknown label: #{yi}" unless v
-          v
+          # use an additional label for unseen values
+          # this is only used during training for the LightGBM eval_set
+          # LightGBM ignores them (only uses seen categories for predictions)
+          # https://github.com/microsoft/LightGBM/issues/1936
+          # the evaluator also ignores them (to be consistent with LightGBM)
+          # but doesn't use this code
+          @labels[yi.to_s] || @labels.size
         end
       end
     end
 
     def inverse_transform(y)