Merge pull request #437 from OceanParcels/indices_debug

field.from_netcdf: indices argument in read-only

Author: delandmeterp

parcels/field.py

@@ -152,8 +152,7 @@ def from_netcdf(cls, filenames, variable, dimensions, indices=None, grid=None,
         if not isinstance(filenames, Iterable) or isinstance(filenames, str):
             filenames = [filenames]
         dimension_filename = dimension_filename if dimension_filename else filenames[0]
-        if indices is None:
-            indices = {}
+        indices = {} if indices is None else indices.copy()
         with NetcdfFileBuffer(dimension_filename, dimensions, indices) as filebuffer:
             lon, lat = filebuffer.read_lonlat
             depth = filebuffer.read_depth

tests/test_fieldset.py

@@ -92,7 +92,9 @@ def test_fieldset_from_file_subsets(indslon, indslat, tmpdir, filename='test_sub
     fieldsetfull = FieldSet.from_data(data, dimensions)
     fieldsetfull.write(filepath)
     indices = {'lon': indslon, 'lat': indslat}
+    indices_back = indices.copy()
     fieldsetsub = FieldSet.from_parcels(filepath, indices=indices)
+    assert indices == indices_back
     assert np.allclose(fieldsetsub.U.lon, fieldsetfull.U.grid.lon[indices['lon']])
     assert np.allclose(fieldsetsub.U.lat, fieldsetfull.U.grid.lat[indices['lat']])
     assert np.allclose(fieldsetsub.V.lon, fieldsetfull.V.grid.lon[indices['lon']])