privatize iotools.srml.format_index and map_columns

Author: kandersolar

pvlib/iotools/srml.py

@@ -60,11 +60,11 @@ def read_srml(filename):
        `http://solardat.uoregon.edu/ <http://solardat.uoregon.edu/>`_
     """
     tsv_data = pd.read_csv(filename, delimiter='\t')
-    data = format_index(tsv_data)
+    data = _format_index(tsv_data)
     # Drop day of year and time columns
     data = data[data.columns[2:]]
 
-    data = data.rename(columns=map_columns)
+    data = data.rename(columns=_map_columns)
 
     # Quality flag columns are all labeled 0 in the original data. They
     # appear immediately after their associated variable and are suffixed
@@ -90,7 +90,7 @@ def read_srml(filename):
     return data
 
 
-def map_columns(col):
+def _map_columns(col):
     """Map data element numbers to pvlib names.
 
     Parameters
@@ -118,7 +118,7 @@ def map_columns(col):
         return col
 
 
-def format_index(df):
+def _format_index(df):
     """Create a datetime index from day of year, and time columns.
 
     Parameters