Natural Language Processing: Python and NLTK

Training a chunker with NLTK-Trainer

At the end of the previous chapter, Chapter 4, Part-of-speech Tagging, we introduced NLTK-Trainer and the train_tagger.py script. In this recipe, we will cover the script for training chunkers: train_chunker.py.

Note

You can find NLTK-Trainer at https://github.com/japerk/nltk-trainer and the online documentation at http://nltk-trainer.readthedocs.org/.

How to do it...

As with train_tagger.py, the only required argument to train_chunker.py is the name of a corpus. In this case, we need a corpus that provides a chunked_sents() method, such as treebank_chunk. Here's an example of running train_chunker.py on treebank_chunk:

$ python train_chunker.py treebank_chunk
loading treebank_chunk
4009 chunks, training on 4009 ...