python语法分析问题,这是什么问题,怎么改啊
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发布时间：2022-04-27 03:43
共1个回答
热心网友
时间：2022-04-18 22:53
没有用过nltk这个机器学习的库。不过从语法解析上看。你的格式不对。
我略略查了一下，它的语法应该是这样子
S -> 'NP' | 'VP'
PP -> 'P' | 'NP'
你修改一下看看。另外它的noterminals似乎是一个特殊含义。不是种换行符。下面是一个较完整的示例
-
def cfg_demo():
"""
A demonstration showing how C{ContextFreeGrammar}s can be created and used.
"""
from nltk import nonterminals, Proction, parse_cfg
# Create some nonterminals
S, NP, VP, PP = nonterminals('S, NP, VP, PP')
N, V, P, Det = nonterminals('N, V, P, Det')
VP_slash_NP = VP/NP
print 'Some nonterminals:', [S, NP, VP, PP, N, V, P, Det, VP/NP]
print ' S.symbol() =>', `S.symbol()`
print
print Proction(S, [NP])
# Create some Grammar Proctions
grammar = parse_cfg("""
S -> NP VP
PP -> P NP
NP -> Det N | NP PP
VP -> V NP | VP PP
Det -> 'a' | 'the'
N -> 'dog' | 'cat'
V -> 'chased' | 'sat'
P -> 'on' | 'in'
""")
print 'A Grammar:', `grammar`
print ' grammar.start() =>', `grammar.start()`
print ' grammar.proctions() =>',
# Use string.replace(...) is to line-wrap the output.
print `grammar.proctions()`.replace(',', ',\n'+' '*25)
print
print 'Coverage of input words by a grammar:'
-
def cfg_demo():"""
A demonstration showing how C{ContextFreeGrammar}s can be created and used.
"""
from nltk import nonterminals, Proction, parse_cfg
# Create some nonterminals
S, NP, VP, PP = nonterminals('S, NP, VP, PP')
N, V, P, Det = nonterminals('N, V, P, Det')
VP_slash_NP = VP/NP
print 'Some nonterminals:', [S, NP, VP, PP, N, V, P, Det, VP/NP]
print ' S.symbol() =>', `S.symbol()`
print Proction(S, [NP])
# Create some Grammar Proctions
grammar = parse_cfg("""
S -> NP VP
PP -> P NP
NP -> Det N | NP PP
VP -> V NP | VP PP
Det -> 'a' | 'the'
N -> 'dog' | 'cat'
V -> 'chased' | 'sat'
P -> 'on' | 'in'
""")
print 'A Grammar:', `grammar`
print ' grammar.start() =>', `grammar.start()`
print ' grammar.proctions() =>',
# Use string.replace(...) is to line-wrap the output.
print `grammar.proctions()`.replace(',', ',\n'+' '*25)
print 'Coverage of input words by a grammar:'
-
from nltk import nonterminals, Proction, parse_cfg # Create some nonterminals S, NP, VP, PP = nonterminals('S, NP, VP, PP') N, V, P, Det = nonterminals('N, V, P, Det') VP_slash_NP = VP/NP print 'Some nonterminals:', [S, NP, VP, PP, N, V, P, Det, VP/NP] print ' S.symbol() =>', `S.symbol()` print print Proction(S, [NP]) # Create some Grammar Proctions grammar = parse_cfg(""" S -> NP VP PP -> P NP NP -> Det N | NP PP VP -> V NP | VP PP Det -> 'a' | 'the' N -> 'dog' | 'cat' V -> 'chased' | 'sat' P -> 'on' | 'in' """) print 'A Grammar:', `grammar` print ' grammar.start() =>', `grammar.start()` print ' grammar.proctions() =>', # Use string.replace(...) is to line-wrap the output. print `grammar.proctions()`.replace(',', ',\n'+' '*25) print print 'Coverage of input words by a grammar:' print grammar.covers(['a','dog']) print grammar.covers(['a','toy']) toy_pcfg1 = parse_pcfg(""" S -> NP VP [1.0] NP -> Det N [0.5] | NP PP [0.25] | 'John' [0.1] | 'I' [0.15] Det -> 'the' [0.8] | 'my' [0.2] N -> 'man' [0.5] | 'telescope' [0.5] VP -> VP PP [0.1] | V NP [0.7] | V [0.2] V -> 'ate' [0.35] | 'saw' [0.65] PP -> P NP [1.0] P -> 'with' [0.61] | 'under' [0.39] """) toy_pcfg2 = parse_pcfg(""" S -> NP VP [1.0] VP -> V NP [.59] VP -> V [.40] VP -> VP PP [.01] NP -> Det N [.41] NP -> Name [.28] NP -> NP PP [.31] PP -> P NP [1.0] V -> 'saw' [.21] V -> 'ate' [.51] V -> 'ran' [.28] N -> 'boy' [.11] N -> 'cookie' [.12] N -> 'table' [.13] N -> 'telescope' [.14] N -> 'hill' [.5] Name -> 'Jack' [.52] Name -> 'Bob' [.48] P -> 'with' [.61] P -> 'under' [.39] Det -> 'the' [.41] Det -> 'a' [.31] Det -> 'my' [.28] """)
