During preprocessing, lowercase variable name keys in itemid map

and reference ranges to make sure we don't fall victim to inconsistent
cases in variable names.

mimic3benchmark/preprocessing.py

@@ -79,9 +79,8 @@ def make_phenotype_label_matrix(phenotypes, stays=None):
 
 def read_itemid_to_variable_map(fn, variable_column='LEVEL2'):
     var_map = DataFrame.from_csv(fn, index_col=None).fillna('').astype(str)
-
+    var_map[variable_column] = var_map[variable_column].apply(lambda s: s.lower())
     var_map.COUNT = var_map.COUNT.astype(int)
-
     var_map = var_map.ix[(var_map[variable_column] != '') & (var_map.COUNT>0)]
     var_map = var_map.ix[(var_map.STATUS == 'ready')]
     var_map.ITEMID = var_map.ITEMID.astype(int)
@@ -96,6 +95,7 @@ def read_variable_ranges(fn, variable_column='LEVEL2'):
     to_rename = dict(zip(columns, [ c.replace(' ', '_') for c in columns ]))
     to_rename[variable_column] = 'VARIABLE'
     var_ranges = DataFrame.from_csv(fn, index_col=None)
+    var_ranges = var_ranges[variable_column].apply(lambda s: s.lower())
     var_ranges = var_ranges[columns]
     var_ranges.rename_axis(to_rename, axis=1, inplace=True)
     var_ranges = var_ranges.drop_duplicates(subset='VARIABLE', keep='first')