fixes issue with cloud_cover_to_transmittance_linear ignoring offset kw arg

KonstantinTr · wholmgren · commit 2d08caaa5e94 · 2017-08-10T09:31:51.000-07:00
* fix for issue pvlib#343 Now, passed 'offset' parameter are used instead of it's default value. * test for issue pvlib#343
diff --git a/pvlib/forecast.py b/pvlib/forecast.py
@@ -473,7 +473,7 @@ def cloud_cover_to_transmittance_linear(self, cloud_cover, offset=0.75,
         ghi : numeric
             Estimated GHI.
         """
-        transmittance = ((100.0 - cloud_cover) / 100.0) * 0.75
+        transmittance = ((100.0 - cloud_cover) / 100.0) * offset
 
         return transmittance
 
diff --git a/pvlib/test/test_forecast.py b/pvlib/test/test_forecast.py
@@ -129,6 +129,7 @@ def test_cloud_cover_to_transmittance_linear():
     amodel = GFS()
     assert_allclose(amodel.cloud_cover_to_transmittance_linear(0), 0.75)
     assert_allclose(amodel.cloud_cover_to_transmittance_linear(100), 0.0)
+    assert_allclose(amodel.cloud_cover_to_transmittance_linear(0, 0.5), 0.5)
 
 
 def test_cloud_cover_to_ghi_linear():
