Fix tf-idf again (#2986)
Fix tf-idf again (#2986)

Fix 53aaa842ed4cb3b8619032eb6c5deedef32fdbc0
Fix #2974
kuza55/keras,kemaswill/keras,keras-team/keras,dolaameng/keras,relh/keras,DeepGnosis/keras,keras-team/keras,nebw/keras