temporal.mapcalc: added warning before removing empty maps

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@71436 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/python/temporal/mapcalc.py

@@ -319,6 +319,9 @@ def dataset_mapcalculator(inputs, output, type, expression, base, method,
 
         # Remove empty maps
         if len(empty_maps) > 0:
+            n_empty, n_tot = len(empty_maps), len(map_list)
+            msgr.warning(_("Removing {}/{} ({}%) maps because empty..."
+                           ).format(n_empty, n_tot, n_empty * 100. / n_tot))
             names = ""
             count = 0
             for map in empty_maps: