Add comment as requested by Jan

Author: mfeurer

openml/datasets/dataset.py

@@ -408,6 +408,8 @@ def _unpack_categories(series, categories):
                 col.append(categories[int(x)])
             except (TypeError, ValueError):
                 col.append(np.nan)
+        # We require two lines to create a series of categories as detailed here:
+        # https://pandas.pydata.org/pandas-docs/version/0.24/user_guide/categorical.html#series-creation  # noqa E501
         raw_cat = pd.Categorical(col, ordered=True, categories=categories)
         return pd.Series(raw_cat, index=series.index, name=series.name)
 

openml/runs/run.py

@@ -1,7 +1,7 @@
 from collections import OrderedDict
 import pickle
 import time
-from typing import Any, IO, TextIO
+from typing import Any, IO, TextIO  # noqa F401
 import os
 
 import arff