PennToPCFG 从Penn Treebank学习未词法化的PCFG

#PennToPCFG从Penn Treebank风格的语料库（例如华尔街日报）中学习未词法化的PCFG。需要NLTK2来读取树库和处理树。 ＃＃用法usage: PennToPCFG.py [-h] [-p PENN] [-g GRAMMAR] [-pe PENNEVAL] [-s SENTENCES] [-t TREES] [-l LENGTH] [-b DEBINARIZE] Learns an unlexicalised PCFG from a Penn Treebank file optional arguments: -h, --help show this help message and exit -p PENN, --penn PENN The Penn