forecast compat with pandas 1.0, fix bug in Location tz handling (#879)

* fix location tz bug with datetime.timezone.utc

* update whatsnew

* issue in whatsnew

* fix whatsnew class typo

Author: wholmgren

docs/sphinx/source/whatsnew/v0.7.2.rst

@@ -3,6 +3,11 @@
 v0.7.2 (Month day, year)
 -------------------------
 
+API Changes
+~~~~~~~~~~~
+* :py:class:`pvlib.forecast.ForecastModel` now requires ``start`` and ``end``
+  arguments to be tz-localized. (:issue:`877`, :pull:`879`)
+
 Enhancements
 ~~~~~~~~~~~~
 * TMY3 dataframe returned by :py:func:`~pvlib.iotools.read_tmy3` now contains
@@ -15,6 +20,8 @@ Bug fixes
   a leap year (:pull:`866`)
 * Implement NREL Developer Network API key for consistent success with API
   calls in :py:mod:`pvlib.tests.iotools.test_psm3` (:pull:`873`)
+* Fix issue with :py:class:`pvlib.location.Location` creation when
+  passing ``tz=datetime.timezone.utc`` (:pull:`879`)
 
 Documentation
 ~~~~~~~~~~~~~
@@ -29,3 +36,6 @@ Contributors
 * Mark Mikofski (:ghuser:`mikofski`)
 * Cliff Hansen (:ghuser:`cwhanse`)
 * Cameron T. Stark (:ghuser:`camerontstark`)
+* Will Holmgren (:ghuser:`wholmgren`)
+* Kevin Anderson (:ghuser:`kanderso-nrel`)
+* Karthikeyan Singaravelan (:ghuser:`tirkarthi`)

pvlib/forecast.py

@@ -165,6 +165,25 @@ def set_dataset(self):
         self.ncss = NCSS(self.access_url)
         self.query = self.ncss.query()
 
+    def set_query_time_range(self, start, end):
+        """
+        Parameters
+        ----------
+        start : datetime.datetime, pandas.Timestamp
+            Must be tz-localized.
+        end : datetime.datetime, pandas.Timestamp
+            Must be tz-localized.
+
+        Notes
+        -----
+        Assigns ``self.start``, ``self.end``. Modifies ``self.query``
+        """
+        self.start = pd.Timestamp(start)
+        self.end = pd.Timestamp(end)
+        if self.start.tz is None or self.end.tz is None:
+            raise TypeError('start and end must be tz-localized')
+        self.query.time_range(self.start, self.end)
+
     def set_query_latlon(self):
         '''
         Sets the NCSS query location latitude and longitude.
@@ -180,24 +199,24 @@ def set_query_latlon(self):
             self.lbox = False
             self.query.lonlat_point(self.longitude, self.latitude)
 
-    def set_location(self, time, latitude, longitude):
+    def set_location(self, tz, latitude, longitude):
         '''
         Sets the location for the query.
 
         Parameters
         ----------
-        time: datetime or DatetimeIndex
-            Time range of the query.
-        '''
-        if isinstance(time, datetime.datetime):
-            tzinfo = time.tzinfo
-        else:
-            tzinfo = time.tz
+        tz: tzinfo
+            Timezone of the query
+        latitude: float
+            Latitude of the query
+        longitude: float
+            Longitude of the query
 
-        if tzinfo is None:
-            self.location = Location(latitude, longitude)
-        else:
-            self.location = Location(latitude, longitude, tz=tzinfo)
+        Notes
+        -----
+        Assigns ``self.location``.
+        '''
+        self.location = Location(latitude, longitude, tz=tz)
 
     def get_data(self, latitude, longitude, start, end,
                  vert_level=None, query_variables=None,
@@ -243,14 +262,12 @@ def get_data(self, latitude, longitude, start, end,
         else:
             self.query_variables = query_variables
 
+        self.set_query_time_range(start, end)
+
         self.latitude = latitude
         self.longitude = longitude
         self.set_query_latlon()  # modifies self.query
-        self.set_location(start, latitude, longitude)
-
-        self.start = start
-        self.end = end
-        self.query.time_range(self.start, self.end)
+        self.set_location(self.start.tz, latitude, longitude)
 
         if self.vert_level is not None:
             self.query.vertical_level(self.vert_level)

pvlib/location.py

@@ -66,6 +66,9 @@ def __init__(self, latitude, longitude, tz='UTC', altitude=0,
         if isinstance(tz, str):
             self.tz = tz
             self.pytz = pytz.timezone(tz)
+        elif isinstance(tz, datetime.timezone):
+            self.tz = 'UTC'
+            self.pytz = pytz.UTC
         elif isinstance(tz, datetime.tzinfo):
             self.tz = tz.zone
             self.pytz = tz

pvlib/tests/test_forecast.py

@@ -1,5 +1,4 @@
-from datetime import datetime, timedelta
-from pytz import timezone
+from datetime import datetime, timedelta, timezone
 import warnings
 
 import pandas as pd
@@ -114,7 +113,7 @@ def test_vert_level():
 @requires_siphon
 def test_datetime():
     amodel = NAM()
-    start = datetime.now()
+    start = datetime.now(tz=timezone.utc)
     end = start + timedelta(days=1)
     amodel.get_processed_data(_latitude, _longitude, start, end)
 
@@ -138,7 +137,6 @@ def test_full():
     GFS(set_type='full')
 
 
-@requires_siphon
 def test_temp_convert():
     amodel = GFS()
     data = pd.DataFrame({'temp_air': [273.15]})
@@ -157,14 +155,19 @@ def test_temp_convert():
 #                                  variables=new_variables)
 
 
-@requires_siphon
 def test_set_location():
     amodel = GFS()
     latitude, longitude = 32.2, -110.9
-    time = datetime.now(timezone('UTC'))
+    time = 'UTC'
     amodel.set_location(time, latitude, longitude)
 
 
+def test_set_query_time_range_tzfail():
+    amodel = GFS()
+    with pytest.raises(TypeError):
+        amodel.set_query_time_range(datetime.now(), datetime.now())
+
+
 def test_cloud_cover_to_transmittance_linear():
     amodel = GFS()
     assert_allclose(amodel.cloud_cover_to_transmittance_linear(0), 0.75)

pvlib/tests/test_location.py

@@ -29,6 +29,7 @@ def test_location_all():
 
 @pytest.mark.parametrize('tz', [
     pytz.timezone('US/Arizona'), 'America/Phoenix',  -7, -7.0,
+    datetime.timezone.utc
 ])
 def test_location_tz(tz):
     Location(32.2, -111, tz)