[utils] fixed the map_label function (hopefully)

bob/learn/pytorch/datasets/utils.py

@@ -84,8 +84,14 @@ class ToGray(object):
 def map_labels(raw_labels, start_index=0):
   """
   Map the ID label to [0 - # of IDs]
+  
+  Parameters
+  ----------
+  raw_labels: list of int
+    The labels of the samples 
+  
   """
-  possible_labels = list(set(raw_labels))
+  possible_labels = sorted(list(set(raw_labels)))
   labels = numpy.array(raw_labels)
 
   for i in range(len(possible_labels)):