Spatial aggregation fix (#317)

* Update dimension.py

Correct spatial aggregation method to 'mean' for both 'mm/h' and 'mm' precipitation units.

* Update test_utils_dimension.py

Correct spatial aggregation test.

Co-authored-by: Daan Buekenhout <[email protected]>

Author: dbkhout

pysteps/tests/test_utils_dimension.py

@@ -150,7 +150,7 @@ def test_aggregate_fields_time(R, metadata, time_window_min, ignore_nan, expecte
         {"unit": "mm", "xpixelsize": 1, "ypixelsize": 1},
         2,
         False,
-        4 * np.ones((1, 5, 5)),
+        np.ones((1, 5, 5)),
     ),
     (
         np.ones((1, 10, 10)),

pysteps/utils/dimension.py

@@ -197,10 +197,8 @@ def aggregate_fields_space(R, metadata, space_window, ignore_nan=False):
 
     # specify the operator to be used to aggregate the values
     # within the space window
-    if unit == "mm/h":
+    if unit == "mm/h" or unit == "mm":
         method = "mean"
-    elif unit == "mm":
-        method = "sum"
     else:
         raise ValueError(
             "can only aggregate units of 'mm/h' or 'mm' " + "not %s" % unit