Error running the example in README #12
Description
Hi, I cloned the master branch and tried the example in README, but encountered the following error. Could anyone know how to fix it? Thanks!
Python 2.7.12 (default, Jul 18 2016, 15:02:52)
[GCC 4.8.4] on linux2
Type "help", "copyright", "credits" or "license" for more information.
from stat_parser import Parser
parser = Parser()
print parser.parse("How can the net amount of entropy of the universe be massively decreased?")
Traceback (most recent call last):
File "", line 1, in
File "stat_parser/parser.py", line 112, in nltk_parse
return nltk_tree(self.raw_parse(sentence))
File "stat_parser/parser.py", line 107, in raw_parse
tree = self.norm_parse(sentence)
File "stat_parser/parser.py", line 104, in norm_parse
return CKY(self.pcfg, norm_words)
File "stat_parser/parser.py", line 74, in CKY
_, top = max([(pi[1, n, X], bp[1, n, X]) for X in pcfg.N])
ValueError: max() arg is an empty sequence