cfg.py 文件源码

def demo2():
    from nltk import Nonterminal, Production, CFG
    nonterminals = 'S VP NP PP P N Name V Det'
    (S, VP, NP, PP, P, N, Name, V, Det) = [Nonterminal(s)
                                           for s in nonterminals.split()]
    productions = (
        # Syntactic Productions
        Production(S, [NP, VP]),
        Production(NP, [Det, N]),
        Production(NP, [NP, PP]),
        Production(VP, [VP, PP]),
        Production(VP, [V, NP, PP]),
        Production(VP, [V, NP]),
        Production(PP, [P, NP]),
        Production(PP, []),

        Production(PP, ['up', 'over', NP]),

        # Lexical Productions
        Production(NP, ['I']),   Production(Det, ['the']),
        Production(Det, ['a']),  Production(N, ['man']),
        Production(V, ['saw']),  Production(P, ['in']),
        Production(P, ['with']), Production(N, ['park']),
        Production(N, ['dog']),  Production(N, ['statue']),
        Production(Det, ['my']),
        )
    grammar = CFG(S, productions)

    text = 'I saw a man in the park'.split()
    d=CFGDemo(grammar, text)
    d.mainloop()

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# Old Demo
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