Fix reverse mapping issue and undesirable column reordering in get_psm3 (#1648)

* Fix mapping of request variables

* I've missed stickler

* Add column order check

* Fix typo

* Update pvlib/tests/iotools/test_psm3.py

Co-authored-by: Kevin Anderson <kevin.anderson@nrel.gov>

* Add whatsnew entry

* Update variable map

---------

Co-authored-by: Kevin Anderson <kevin.anderson@nrel.gov>

Author: AdamRJensen

docs/sphinx/source/whatsnew/v0.9.5.rst

@@ -20,6 +20,9 @@ Enhancements
 
 Bug fixes
 ~~~~~~~~~
+* Fixed incorrect mapping of requested parameters names when using the ``get_psm3``
+  function. Also fixed the random reordering of the dataframe columns.
+  (:issue:`1629`, :issue:`1647`, :pull:`1648`)
 
 
 Testing
@@ -45,4 +48,5 @@ Contributors
 ~~~~~~~~~~~~
 * Kevin Anderson (:ghuser:`kanderso-nrel`)
 * Will Holmgren (:ghuser:`wholmgren`)
+* Adam R. Jensen (:ghuser:`adamrjensen`)
 * Pratham Chauhan (:ghuser:`ooprathamm`)

pvlib/iotools/psm3.py

@@ -15,13 +15,12 @@
 TMY_URL = NSRDB_API_BASE + "/api/nsrdb/v2/solar/psm3-tmy-download.csv"
 PSM5MIN_URL = NSRDB_API_BASE + "/api/nsrdb/v2/solar/psm3-5min-download.csv"
 
-# 'relative_humidity', 'total_precipitable_water' are not available
 ATTRIBUTES = (
     'air_temperature', 'dew_point', 'dhi', 'dni', 'ghi', 'surface_albedo',
     'surface_pressure', 'wind_direction', 'wind_speed')
 PVLIB_PYTHON = 'pvlib python'
 
-# Dictionary mapping PSM3 names to pvlib names
+# Dictionary mapping PSM3 response names to pvlib names
 VARIABLE_MAP = {
     'GHI': 'ghi',
     'DHI': 'dhi',
@@ -31,15 +30,36 @@
     'Clearsky DNI': 'dni_clear',
     'Solar Zenith Angle': 'solar_zenith',
     'Temperature': 'temp_air',
-    'Relative Humidity': 'relative_humidity',
     'Dew point': 'temp_dew',
+    'Relative Humidity': 'relative_humidity',
     'Pressure': 'pressure',
-    'Wind Direction': 'wind_direction',
     'Wind Speed': 'wind_speed',
+    'Wind Direction': 'wind_direction',
     'Surface Albedo': 'albedo',
     'Precipitable Water': 'precipitable_water',
 }
 
+# Dictionary mapping pvlib names to PSM3 request names
+# Note, PSM3 uses different names for the same variables in the
+# response and the request
+REQUEST_VARIABLE_MAP = {
+    'ghi': 'ghi',
+    'dhi': 'dhi',
+    'dni': 'dni',
+    'ghi_clear': 'clearsky_dhi',
+    'dhi_clear': 'clearsky_dhi',
+    'dni_clear': 'clearsky_dni',
+    'zenith': 'solar_zenith_angle',
+    'temp_air': 'air_temperature',
+    'temp_dew': 'dew_point',
+    'relative_humidity': 'relative_humidity',
+    'pressure': 'surface_pressure',
+    'wind_speed': 'wind_speed',
+    'wind_direction': 'wind_direction',
+    'albedo': 'surface_albedo',
+    'precipitable_water': 'total_precipitable_water',
+}
+
 
 def get_psm3(latitude, longitude, api_key, email, names='tmy', interval=60,
              attributes=ATTRIBUTES, leap_day=None, full_name=PVLIB_PYTHON,
@@ -74,7 +94,7 @@ def get_psm3(latitude, longitude, api_key, email, names='tmy', interval=60,
         meteorological fields to fetch. If not specified, defaults to
         ``pvlib.iotools.psm3.ATTRIBUTES``. See references [2]_, [3]_, and [4]_
         for lists of available fields. Alternatively, pvlib names may also be
-        used (e.g. 'ghi' rather than 'GHI'); see :const:`VARIABLE_MAP`.
+        used (e.g. 'ghi' rather than 'GHI'); see :const:`REQUEST_VARIABLE_MAP`.
     leap_day : boolean, default False
         include leap day in the results. Only used for single-year requests
         (i.e., it is ignored for tmy/tgy/tdy requests).
@@ -158,12 +178,8 @@ def get_psm3(latitude, longitude, api_key, email, names='tmy', interval=60,
     # convert to string to accomodate integer years being passed in
     names = str(names)
 
-    # convert pvlib names in attributes to psm3 convention (reverse mapping)
-    # unlike psm3 columns, attributes are lower case and with underscores
-    amap = {value: key.lower().replace(' ', '_') for (key, value) in
-            VARIABLE_MAP.items()}
-    attributes = [amap.get(a, a) for a in attributes]
-    attributes = list(set(attributes))  # remove duplicate values
+    # convert pvlib names in attributes to psm3 convention
+    attributes = [REQUEST_VARIABLE_MAP.get(a, a) for a in attributes]
 
     if (leap_day is None) and (not names.startswith('t')):
         warnings.warn(

pvlib/tests/iotools/test_psm3.py

@@ -189,8 +189,10 @@ def test_get_psm3_attribute_mapping(nrel_api_key):
                                names=2019, interval=60,
                                attributes=['ghi', 'wind_speed'],
                                leap_day=False, map_variables=True)
-    assert 'ghi' in data.columns
-    assert 'wind_speed' in data.columns
+    # Check that columns are in the correct order (GH1647)
+    expected_columns = [
+        'Year', 'Month', 'Day', 'Hour', 'Minute', 'ghi', 'wind_speed']
+    pd.testing.assert_index_equal(pd.Index(expected_columns), data.columns)
     assert 'latitude' in meta.keys()
     assert 'longitude' in meta.keys()
     assert 'altitude' in meta.keys()