def encode(dframe, dataset, add_index=True):
"""Encode the columns for `dataset` to slugs and add ID column.
The ID column is the dataset_id for dataset. This is
used to link observations to a specific dataset.
:param dframe: The DataFrame to encode.
:param dataset: The Dataset to use a mapping for.
:param add_index: Add index to the DataFrame, default True.
:returns: A modified `dframe` as a BambooFrame.
"""
dframe = BambooFrame(dframe)
if add_index:
dframe = dframe.add_index()
dframe = dframe.add_id_column(dataset.dataset_id)
encoded_columns_map = dataset.schema.rename_map_for_dframe(dframe)
return dframe.rename(columns=encoded_columns_map)
