numpy 1.16 compatibility (#644)

* fix issues with scalars and xfail

* whatsnew

Author: wholmgren

docs/sphinx/source/whatsnew/v0.6.1.rst

@@ -76,6 +76,8 @@ Bug fixes
 * Fix error in ``pvlib.spa`` when using Python 3.7 on some platforms.
 * Fix error in :func:`pvlib.irradiance._delta_kt_prime_dirint` (:issue:`637`). The error affects
   the first and last values of DNI calculated by the function :func:`pvlib.irradiance.dirint`
+* Fix errors on Python 2.7 and Numpy 1.6. (:issue:`642`)
+* Replace deprecated `np.asscalar` with `array.item()`. (:issue:`642`)
 
 
 Testing

pvlib/irradiance.py

@@ -1131,6 +1131,7 @@ def perez(surface_tilt, surface_azimuth, dhi, dni, dni_extra,
     # sense for small zenith angles, but...) these values will
     # eventually be used as indicies for coeffecient look ups
     ebin = np.digitize(eps, (0., 1.065, 1.23, 1.5, 1.95, 2.8, 4.5, 6.2))
+    ebin = np.array(ebin)  # GH 642
     ebin[np.isnan(eps)] = 0
 
     # correct for 0 indexing in coeffecient lookup

pvlib/singlediode.py

@@ -465,7 +465,7 @@ def _lambertw_v_from_i(resistance_shunt, resistance_series, nNsVth, current,
             I[idx_p] * Rs[idx_p] - a[idx_p] * lambertwterm
 
     if output_is_scalar:
-        return np.asscalar(V)
+        return V.item()
     else:
         return V
 
@@ -528,7 +528,7 @@ def _lambertw_i_from_v(resistance_shunt, resistance_series, nNsVth, voltage,
                                a[idx_p] / Rs[idx_p]) * lambertwterm
 
     if output_is_scalar:
-        return np.asscalar(I)
+        return I.item()
     else:
         return I
 

pvlib/spa.py

@@ -1419,7 +1419,7 @@ def calculate_deltat(year, month):
 
                       -20+32*((y-1820)/100)**2, deltat)
 
-    deltat = np.asscalar(deltat) if np.isscalar(year) & np.isscalar(month)\
+    deltat = deltat.item() if np.isscalar(year) & np.isscalar(month)\
         else deltat
 
     return deltat

pvlib/test/test_irradiance.py

@@ -273,6 +273,8 @@ def test_perez_scalar():
     out = irradiance.perez(40, 180, 118.45831879, 939.95469881,
                            1321.1655834833093, 10.56413562, 144.76567754,
                            1.01688136)
+    # this will fail. out is ndarry with ndim == 0. fix in future version.
+    # assert np.isscalar(out)
     assert_allclose(out, 109.084332)
 
 

pvlib/test/test_solarposition.py

@@ -541,7 +541,6 @@ def test_get_solarposition_altitude(altitude, expected, golden):
     pytest.param(
         None, 'nrel_numba',
         marks=[pytest.mark.xfail(
-            raises=ValueError,
             reason='spa.calculate_deltat not implemented for numba yet')]),
     (67.0, 'nrel_numba')
     ])

pvlib/tools.py

@@ -212,7 +212,7 @@ def _scalar_out(input):
     else:  #
         # works if it's a 1 length array and
         # will throw a ValueError otherwise
-        output = np.asscalar(input)
+        output = input.item()
 
     return output