def update_df():
'''Load newly crawled events, then update document frequency table'''
tf_idf_api = StanfordTFIDFApi()
# load newly crawled events
unanalyzed_events = keyword_dao.load_unanalyzed_event()
# compute incremental document frequency with loaded new events
computed_df = tf_idf_api.compute_df([event['detail'] for event in unanalyzed_events])
# update df table
keyword_dao.update_df_table(computed_df)
# mark analyzed events
keyword_dao.mark_analyzed_event([event['id'] for event in unanalyzed_events])
