Remove warning message for num_threads in pvlib.spa (#2170)

* fix spa numthreads warning interpolation

* add test

* get rid of the warning altogether

* whatsnew

docs/sphinx/source/whatsnew/v0.11.1.rst

@@ -30,6 +30,8 @@ Enhancements
 * Added function for calculating wind speed at different heights,
   :py:func:`pvlib.atmosphere.windspeed_powerlaw`.
   (:issue:`2118`, :pull:`2124`)
+* The multithreaded SPA functions no longer emit a warning when calculating
+  solar positions for short time series. (:pull:`2170`)
 * Implemented closed-form solution for alpha in :py:func:`pvlib.clearsky.detect_clearsky`, 
   obviating the call to scipy.optimize that was prone to runtime errors and minimizing
   computation. (:issue:`2171`, :issue:`2216`, :pull:`2217`).

pvlib/spa.py

@@ -937,8 +937,6 @@ def solar_position_numba(unixtime, lat, lon, elev, pressure, temp, delta_t,
         unixtime = unixtime.astype(np.float64)
 
     if ulength < numthreads:
-        warnings.warn('The number of threads is more than the length of '
-                      'the time array. Only using %s threads.'.format(ulength))
         numthreads = ulength
 
     if numthreads <= 1:

pvlib/tests/test_irradiance.py

@@ -106,7 +106,7 @@ def test_get_extra_radiation_epoch_year():
 @requires_numba
 def test_get_extra_radiation_nrel_numba(times):
     with warnings.catch_warnings():
-        # don't warn on method reload or num threads
+        # don't warn on method reload
         warnings.simplefilter("ignore")
         result = irradiance.get_extra_radiation(
             times, method='nrel', how='numba', numthreads=4)

pvlib/tests/test_solarposition.py

@@ -490,7 +490,7 @@ def test_get_solarposition_deltat(delta_t, method, expected_solpos_multi,
     times = pd.date_range(datetime.datetime(2003, 10, 17, 13, 30, 30),
                           periods=2, freq='D', tz=golden.tz)
     with warnings.catch_warnings():
-        # don't warn on method reload or num threads
+        # don't warn on method reload
         warnings.simplefilter("ignore")
         ephem_data = solarposition.get_solarposition(times, golden.latitude,
                                                      golden.longitude,
@@ -838,7 +838,7 @@ def test_spa_python_numba_physical(expected_solpos, golden_mst):
     times = pd.date_range(datetime.datetime(2003, 10, 17, 12, 30, 30),
                           periods=1, freq='D', tz=golden_mst.tz)
     with warnings.catch_warnings():
-        # don't warn on method reload or num threads
+        # don't warn on method reload
         # ensure that numpy is the most recently used method so that
         # we can use the warns filter below
         warnings.simplefilter("ignore")
@@ -865,7 +865,7 @@ def test_spa_python_numba_physical_dst(expected_solpos, golden):
                           periods=1, freq='D', tz=golden.tz)
 
     with warnings.catch_warnings():
-        # don't warn on method reload or num threads
+        # don't warn on method reload
         warnings.simplefilter("ignore")
         ephem_data = solarposition.spa_python(times, golden.latitude,
                                               golden.longitude, pressure=82000,

pvlib/tests/test_spa.py

@@ -234,7 +234,7 @@ def test_topocentric_azimuth_angle(self):
 
     def test_solar_position(self):
         with warnings.catch_warnings():
-            # don't warn on method reload or num threads
+            # don't warn on method reload
             warnings.simplefilter("ignore")
             spa_out_0 = self.spa.solar_position(
                 unixtimes, lat, lon, elev, pressure, temp, delta_t,