Converting tree labels
As you've seen in previous recipes, parse trees often have a variety of Tree label types that are not present in chunk trees. If you want to use parse trees to train a chunker, then you'll probably want to reduce this variety by converting some of these tree labels to more common label types.
Getting ready
First, we have to decide which Tree labels need to be converted. Let's take a look at that first Tree again:
Immediately, you can see that there are two alternative NP subtrees: NP-SBJ and NP-TMP. Let's convert both of those to NP. The mapping will be as follows:
|
Original Label |
New Label |
|---|---|
|
NP-SBJ |
NP |
|
NP-TMP |
NP |
How to do it... ...
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