nltk/nltk — pull request #371 by kmike (2013-03-18 23:35:31+00:00)
Title: (much) faster HMM supervised training

HiddenMarkovModelTrainer._states and HiddenMarkovModelTrainer._symbols are lists so ``if state not in self._states`` and ``if symbol not in self._symbols`` are O(N). This is fixed by maintaining ``known_symbols`` and ``known_states`` sets.