Added map_variables param in read_tmy3 func

Author: Pratham Chauhan

pvlib/iotools/tmy.py

@@ -3,9 +3,10 @@
 import datetime
 import re
 import pandas as pd
+import warnings
 
 
-def read_tmy3(filename, coerce_year=None, recolumn=True):
+def read_tmy3(filename, coerce_year=None, map_variables=None, recolumn=True):
     """Read a TMY3 file into a pandas dataframe.
 
     Note that values contained in the metadata dictionary are unchanged
@@ -24,6 +25,10 @@ def read_tmy3(filename, coerce_year=None, recolumn=True):
         If supplied, the year of the index will be set to `coerce_year`, except
         for the last index value which will be set to the *next* year so that
         the index increases monotonically.
+    map_variables : bool, default None    
+        If ``True``, apply standard names to TMY3 columns. Typically this
+        results in stripping the units from the column name and issues deprecationWarning 
+        for recolumn 
     recolumn : bool, default True
         If ``True``, apply standard names to TMY3 columns. Typically this
         results in stripping the units from the column name.
@@ -198,9 +203,17 @@ def read_tmy3(filename, coerce_year=None, recolumn=True):
     # NOTE: as of pvlib-0.6.3, min req is pandas-0.18.1, so pd.to_timedelta
     # unit must be in (D,h,m,s,ms,us,ns), but pandas>=0.24 allows unit='hour'
     data.index = data_ymd + pd.to_timedelta(shifted_hour, unit='h')
-
-    if recolumn:
+    
+    if map_variables:
         data = _recolumn(data)  # rename to standard column names
+    elif recolumn:
+        if not map_variables:  # silence warning if map_variables is false
+            data = _recolumn(data)  
+        elif map_variables is None: 
+            data = _recolumn(data)     
+            warnings.warn("recolumn parameter will be retired starting version 0.9.5, please"
+        "use map_variables parameter instead.",DeprecationWarning) 
+            
 
     data = data.tz_localize(int(meta['TZ'] * 3600))