Default tagging provides a baseline for part-of-speech tagging. It simply assigns the same part-of-speech tag to every token. We do this using the
DefaultTagger class. This tagger is useful as a last-resort tagger, and provides a baseline to measure accuracy improvements.
We're going to use the
treebank corpus for most of this chapter because it's a common standard and is quick to load and test. But everything we do should apply equally well to
conll2000, and any other part-of-speech tagged corpus.
DefaultTagger class takes a single argument, the tag you want to apply. We'll give it
NN, which is the tag for a singular noun.
DefaultTagger is most useful when you choose the most common part-of-speech ...