Bug Fix: use cols not df.columns

typo

src/python/py_interface/import_dataframe.py

@@ -210,7 +210,7 @@ def read_csv(
 
     # Create Primary Feature Space
     phi_0 = []
-    for feat_ind, col in enumerate(df.columns):
+    for feat_ind, col in enumerate(cols):
         data, label, unit = extract_col(df, col, False)
         phi_0.append(
             FeatureNode(