Allow for custom irradiations in 'model_parameters'

Author: echedey-ls

pvlib/spectrum/mismatch.py

@@ -261,16 +261,16 @@ def martin_ruiz_spectral_modifier(clearness_index, airmass_absolute,
     airmass_absolute : numeric
         Absolute airmass. Give attention to algorithm used (``kasten1966`` is
         recommended for default parameters of ``monosi``, ``polysi`` and
-        ``asi``, as used in [1]_).
+        ``asi``, see reference [1]_).
 
     cell_type : string or None, default None
         Specifies material of the cell in order to infer model parameters.
         Allowed types are ``monosi``, ``polysi`` and ``asi``, either lower or
         upper case. If None, the parameters must be provided.
 
     model_parameters : dict-like or None, default None
-        In case you want to specify your model parameters use a dict or a
-        ``pd.DataFrame`` as follows:
+        In case you want to specify your model parameters and components
+        use a dict or a ``pd.DataFrame`` as follows:
 
         .. code-block:: python
 
@@ -283,8 +283,7 @@ def martin_ruiz_spectral_modifier(clearness_index, airmass_absolute,
             # Using a pd.DataFrame
             model_parameters = pd.DataFrame({
                 'direct': [a1, b1, c1],
-                'sky diffuse':  [a2, b2, c2],
-                'ground diffuse':  [a3, b3, c3]},
+                'diffuse':  [a2, b2, c2]},
                 index=('a', 'b', 'c'))
 
         ``a``, ``b`` and ``c`` must be scalar.
@@ -300,7 +299,7 @@ def martin_ruiz_spectral_modifier(clearness_index, airmass_absolute,
     Raises
     ------
     ValueError
-        If ``model_parameters`` is not suitable. See example given above.
+        If ``model_parameters`` is not suitable. See examples given above.
     TypeError
         If neither ``cell_type`` nor ``model_parameters`` are given.
     NotImplementedError
@@ -311,7 +310,7 @@ def martin_ruiz_spectral_modifier(clearness_index, airmass_absolute,
     The mismatch modifier is defined as
 
     .. math:: M = c \cdot \exp( a \cdot (K_t - 0.74) + b \cdot (AM - 1.5) )
-    
+
     where ``a``, ``b`` and ``c`` are the model parameters, different for each
     irradiance component.
 
@@ -329,11 +328,11 @@ def martin_ruiz_spectral_modifier(clearness_index, airmass_absolute,
     pvlib.atmosphere.first_solar_spectral_correction
     """
 
-    IRRAD_COMPONENTS = ('direct', 'sky_diffuse', 'ground_diffuse')
+    irrad_components = ('direct', 'sky_diffuse', 'ground_diffuse')
     # Fitting parameters directly from [1]_
     MARTIN_RUIZ_PARAMS = pd.DataFrame(
         index=('monosi', 'polysi', 'asi'),
-        columns=pd.MultiIndex.from_product([IRRAD_COMPONENTS,
+        columns=pd.MultiIndex.from_product([irrad_components,
                                            ('c', 'a', 'b')]),
         data=[  # Direct(c,a,b)  | Sky diffuse(c,a,b) | Ground diffuse(c,a,b)
             [1.029, -.313, 524e-5, .764, -.882, -.0204, .970, -.244, .0129],
@@ -354,14 +353,13 @@ def martin_ruiz_spectral_modifier(clearness_index, airmass_absolute,
     elif cell_type is None and model_parameters is None:
         raise TypeError('You must pass at least "cell_type" '
                         'or "model_parameters" as arguments!')
-    elif model_parameters is not None:
-        # Use user-defined model parameters
-        # Validate 'model_parameters' dict keys and sub-dicts keys
-        if (set(IRRAD_COMPONENTS) != model_parameters.keys()):
-            raise ValueError('You must specify model parameters for exact '
-                             f'irradiance components {IRRAD_COMPONENTS}')
-        if any([{'a', 'b', 'c'} != model_parameters[irrad_type].keys()
-                for irrad_type in IRRAD_COMPONENTS]):
+    elif model_parameters is not None:  # Use user-defined model parameters
+        # Overwrite components, to later iterate over them,
+        # in case user wants to specify their components
+        irrad_components = model_parameters.keys()
+        # Validate 'model_parameters' sub-dicts keys
+        if any([{'a', 'b', 'c'} != set(model_parameters[component].keys())
+                for component in irrad_components]):
             raise ValueError("You must specify model parameters with keys "
                              "'a','b','c' for each irradiation component.")
 
@@ -376,9 +374,8 @@ def martin_ruiz_spectral_modifier(clearness_index, airmass_absolute,
 
     modifiers = pd.Series()
 
-    # Order of irradiations shouldn't be changed
     # Values are tested in return order in test_martin_ruiz_spectral_modifier
-    for irrad_type in IRRAD_COMPONENTS:
+    for irrad_type in irrad_components:
         _coeffs = _params[irrad_type]
 
         modifier = _coeffs['c'] * np.exp(_coeffs['a'] * kt_delta

pvlib/tests/test_spectrum.py

@@ -216,26 +216,23 @@ def test_martin_ruiz_spectral_modifier():
     assert_series_equal(result['ground_diffuse'], expected[2], atol=1e-5)
 
     # test results when giving 'model_parameters' as DataFrame
+    # test custom quantity of components and its names can be given
     clearness_index = np.array([0.56, 0.612, 0.664, 0.716, 0.768, 0.82])
     airmass_absolute = np.array([2, 1.8, 1.6, 1.4, 1.2, 1])
     model_parameters = pd.DataFrame({  # monosi values
         'direct': [1.029, -0.313, 0.00524],
-        'sky diffuse':  [0.764, -0.882, -0.0204],
-        'ground diffuse':  [0.97, -0.244, 0.0129]},
+        'diffuse_sky':  [0.764, -0.882, -0.0204]},
         index=('c', 'a', 'b'))
     expected = (  # Direct / Sky diffuse / Ground diffuse
         np.array([1.09149, 1.07274, 1.05432, 1.03621, 1.01841, 1.00092]),
-        np.array([0.88636, 0.85009, 0.81530, 0.78193, 0.74993, 0.71924]),
-        np.array([1.02011, 1.00465, 0.98943, 0.97443, 0.95967, 0.94513]))
+        np.array([0.88636, 0.85009, 0.81530, 0.78193, 0.74993, 0.71924]))
 
     result = spectrum.martin_ruiz_spectral_modifier(
         clearness_index,
         airmass_absolute,
-        cell_type='asi',
         model_parameters=model_parameters)
     assert_allclose(result['direct'], expected[0], atol=1e-5)
-    assert_allclose(result['sky_diffuse'], expected[1], atol=1e-5)
-    assert_allclose(result['ground_diffuse'], expected[2], atol=1e-5)
+    assert_allclose(result['diffuse_sky'], expected[1], atol=1e-5)
 
     # test warning is raised with both 'cell_type' and 'model_parameters'
     # test results when giving 'model_parameters' as dict
@@ -279,22 +276,9 @@ def test_martin_ruiz_spectral_modifier_errors():
                              'or "model_parameters" as arguments!'):
         _ = spectrum.martin_ruiz_spectral_modifier(clearness_index,
                                                    airmass_absolute)
-    # tests for inadequate "model_parameters"
+    # test for error in params keys
     clearness_index = 0.74
     airmass_absolute = 1.5
-    # test for error on irradiances keys
-    model_parameters = {
-        'direct': {'c': 1.029, 'a': -3.13e-1, 'b': 5.24e-3},
-        'sky_diffuse': {'c': 0.764, 'a': -8.82e-1, 'b': -2.04e-2},
-        ':(': {'c': 0.970, 'a': -2.44e-1, 'b': 1.29e-2}}
-    with pytest.raises(ValueError,
-                       match='You must specify model parameters for exact '
-                             'irradiance components '):
-        _ = spectrum.martin_ruiz_spectral_modifier(
-            clearness_index,
-            airmass_absolute,
-            model_parameters=model_parameters)
-    # test for error on params keys
     model_parameters = {
         'direct': {'c': 1.029, 'a': -3.13e-1, 'b': 5.24e-3},
         'sky_diffuse': {'c': 0.764, 'a': -8.82e-1, 'b': -2.04e-2},