Extracting location chunks
To identify LOCATION chunks, we can make a different kind of ChunkParserI subclass that uses the gazetteers corpus to identify location words. The gazetteers corpus is a WordListCorpusReader class that contains the following location words:
- Country names
- U.S. states and abbreviations
- Major U.S. cities
- Canadian provinces
- Mexican states
How to do it...
The
LocationChunker class, found in chunkers.py, iterates over a tagged sentence looking for words that are found in the gazetteers corpus. When it finds one or more location words, it creates a LOCATION chunk using IOB tags. The helper method iob_locations() is where the IOB LOCATION tags are produced, and the parse() method converts these IOB tags into a Tree:
from nltk.chunk ...
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