Matching Python types for return values of pvsystem.calcparams_* (#1700)

* two decorators for renaming pd.Series in a function

* calcparams_* Rs return value to match temp_cell type

* adding tests for pd.Series naming and resistance_series type conversion

* methods for converting between numeric-type values

* adding more tests and clarifying documentation

* rename pdSeries clear name decorator and move it to pvlib.tools

* adding support for scalar to np.ndarray of any shape

* updating match_shape docstring

* fixing syntax error

* fix stickler issues

* different approach

* remove unnecessary asserts

* remove file

* update whatsnew

* add tests for all scalar inputs, and pass np.arrays to assert_allclose

* Update docs/sphinx/source/whatsnew/v0.10.0.rst

Co-authored-by: Cliff Hansen <cwhanse@sandia.gov>

* if condition swap, tests for tools.get_pandas_index, tests for returned Python type

* fix typo in docstring

* correct calcparams_cec test, and add test for calcparams_pvsyst all scalars

---------

Co-authored-by: Cliff Hansen <cwhanse@sandia.gov>

Author: reepoi

docs/sphinx/source/whatsnew/v0.10.0.rst

@@ -29,6 +29,11 @@ Deprecations
 
 Enhancements
 ~~~~~~~~~~~~
+* The return values of :py:func:`pvlib.pvsystem.calcparams_desoto`,
+  :py:func:`pvlib.pvsystem.calcparams_cec`, and
+  :py:func:`pvlib.pvsystem.calcparams_pvsyst` are all numeric types and have
+  the same Python type as the `effective_irradiance` and `temp_cell` parameters. (:issue:`1626`, :pull:`1700`)
+
 * Added `map_variables` parameter to :py:func:`pvlib.iotools.read_srml`
   and :py:func:`pvlib.iotools.read_srml_month_from_solardat` (:pull:`1773`)
 * Allow passing keyword arguments to :py:func:`scipy:scipy.optimize.brentq` and

pvlib/pvsystem.py

@@ -21,6 +21,7 @@
 from pvlib import (atmosphere, iam, inverter, irradiance,
                    singlediode as _singlediode, spectrum, temperature)
 from pvlib.tools import _build_kwargs, _build_args
+import pvlib.tools as tools
 
 
 # a dict of required parameter names for each DC power model
@@ -1540,7 +1541,7 @@ def calcparams_desoto(effective_irradiance, temp_cell,
     saturation_current : numeric
         Diode saturation curent in amperes
 
-    resistance_series : float
+    resistance_series : numeric
         Series resistance in ohms
 
     resistance_shunt : numeric
@@ -1663,9 +1664,21 @@ def calcparams_desoto(effective_irradiance, temp_cell,
     # use errstate to silence divide by warning
     with np.errstate(divide='ignore'):
         Rsh = R_sh_ref * (irrad_ref / effective_irradiance)
+
     Rs = R_s
 
-    return IL, I0, Rs, Rsh, nNsVth
+    numeric_args = (effective_irradiance, temp_cell)
+    out = (IL, I0, Rs, Rsh, nNsVth)
+
+    if all(map(np.isscalar, numeric_args)):
+        return out
+
+    index = tools.get_pandas_index(*numeric_args)
+
+    if index is None:
+        return np.broadcast_arrays(*out)
+
+    return tuple(pd.Series(a, index=index).rename(None) for a in out)
 
 
 def calcparams_cec(effective_irradiance, temp_cell,
@@ -1744,7 +1757,7 @@ def calcparams_cec(effective_irradiance, temp_cell,
     saturation_current : numeric
         Diode saturation curent in amperes
 
-    resistance_series : float
+    resistance_series : numeric
         Series resistance in ohms
 
     resistance_shunt : numeric
@@ -1861,7 +1874,7 @@ def calcparams_pvsyst(effective_irradiance, temp_cell,
     saturation_current : numeric
         Diode saturation current in amperes
 
-    resistance_series : float
+    resistance_series : numeric
         Series resistance in ohms
 
     resistance_shunt : numeric
@@ -1920,7 +1933,18 @@ def calcparams_pvsyst(effective_irradiance, temp_cell,
 
     Rs = R_s
 
-    return IL, I0, Rs, Rsh, nNsVth
+    numeric_args = (effective_irradiance, temp_cell)
+    out = (IL, I0, Rs, Rsh, nNsVth)
+
+    if all(map(np.isscalar, numeric_args)):
+        return out
+
+    index = tools.get_pandas_index(*numeric_args)
+
+    if index is None:
+        return np.broadcast_arrays(*out)
+
+    return tuple(pd.Series(a, index=index).rename(None) for a in out)
 
 
 def retrieve_sam(name=None, path=None):