I am working on an information extractor specifically purposed with parsing relationships between entities such as movies, directors, and actors. NLTK appears to provide the necessary tools to construct such a system. However, it is not clear how one would go about adding custom labels (e.g. actor, director, movie title).
Similarly, Chapter 7 of the NLTK Book discusses information extraction using a named entity recognizer, but it glosses over labeling details.
So, I have two questions:
How would I add custom labels? If I have bare lists of relevant named entities (e.g. movies, actors, etc.), how can I include them as features? It appears that I would need to use IOB format, but I am unsure about how to do this when I only have lists of named entities.