NLTK Chart Parser无法打印 [英] NLTK Chart Parser is not printing

问题描述

这是代码:

groucho_grammar = nltk.CFG.fromstring("""
S -> V NP PP CONJ V NP PP
PP -> PRP NP 
NP -> Det N | PRP N |DET ADJ CONJ ADJ N P 
Det -> 'a' | 'every' | 'all'
N -> 'work'  | 'Word Document' | 'results' | 'step'
ADJ -> 'intermediate' | 'final'
V -> 'Describe' | 'present' 
P -> 'of' | 'in'
CONJ -> 'and'
PRP -> 'your'
""")

sent = ['Describe', 'every', 'step' ,'of', 'your', 'work', 'and' ,\
        'present', 'all', 'intermediate' ,'and' ,'final', 'results', 'in' ,'a', 'Word Document']
parser = nltk.ChartParser(groucho_grammar)
for tree in parser.parse(sent):
    print(tree)

当我这样做时，它可以正常运行，但不会打印任何语法树.我不确定在这里我做错了什么.我遵循了nltk书中的指导原则，但是并没有帮助.

When I do this, It runs without any errors but it doesn't print any grammar trees. I'm not sure what I am doing wrong here. I followed the guidelines in the nltk book but that hasnt helped.

推荐答案

始终以小写形式编写CFG语法，请参见

Always write the CFG grammar in bite-size, see Python and NLTK: How to analyze sentence grammar?

让我们首先尝试处理describe your work.

Let's try to handle describe your work first.

import nltk

your_grammar = nltk.CFG.fromstring("""
S -> V NP
V -> 'describe' | 'present'
NP -> PRP N 
PRP -> 'your' 
N -> 'work'
""")

parser = nltk.ChartParser(your_grammar)
sent = 'describe your work'.split()
print (list(parser.parse(sent)))

[输出]:

[Tree('S', [Tree('V', ['describe']), Tree('NP', [Tree('PRP', ['your']), Tree('N', ['work'])])])]

现在让我们尝试describe every step of your work:

Now let's try describe every step of your work:

import nltk

your_grammar = nltk.CFG.fromstring("""
S -> V NP
V -> 'describe' | 'present'
NP -> PRP N | DT N PP 
PRP -> 'your' 
N -> 'work' | 'step'
PP -> P NP
P -> 'of' 
DT -> 'every'
""")

parser = nltk.ChartParser(your_grammar)
sent = 'describe every step of your work'.split()
print (list(parser.parse(sent)))

[输出]:

[Tree('S', [Tree('V', ['describe']), Tree('NP', [Tree('DT', ['every']), Tree('N', ['step']), Tree('PP', [Tree('P', ['of']), Tree('NP', [Tree('PRP', ['your']), Tree('N', ['work'])])])])])]

现在让我们尝试present final results in a Word Document:

Now let's try present final results in a Word Document:

import nltk

your_grammar = nltk.CFG.fromstring("""
S -> V NP
V -> 'describe' | 'present'
NP -> PRP N | DT N PP | DT N | ADJ N PP
PRP -> 'your' 
N -> 'work' | 'step' | 'results' | 'Word_Document'
PP -> P NP
P -> 'of' | 'in'
DT -> 'every' | 'a'
ADJ -> 'final'
""")

parser = nltk.ChartParser(your_grammar)
#sent = 'describe every step of your work'.split()
sent = 'present final results in a Word_Document'.split()
print (list(parser.parse(sent)))

[输出]:

[Tree('S', [Tree('V', ['present']), Tree('NP', [Tree('ADJ', ['final']), Tree('N', ['results']), Tree('PP', [Tree('P', ['in']), Tree('NP', [Tree('DT', ['a']), Tree('N', ['Word_Document'])])])])])]

现在，我们为present all final results in a Word Document添加NP -> DT NP:

Now, let's add NP -> DT NP for present all final results in a Word Document:

import nltk

your_grammar = nltk.CFG.fromstring("""
S -> V NP
V -> 'describe' | 'present'
NP -> PRP N | DT N PP | DT N | ADJ N PP | DT NP
PRP -> 'your'
N -> 'work' | 'step' | 'results' | 'Word_Document'
PP -> P NP
P -> 'of' | 'in'
DT -> 'every' | 'a' | 'all'
ADJ -> 'final'
""")

parser = nltk.ChartParser(your_grammar)
#sent = 'describe every step of your work'.split()
sent = 'present all final results in a Word_Document'.split()
print (list(parser.parse(sent)))

[输出]:

[Tree('S', [Tree('V', ['present']), Tree('NP', [Tree('DT', ['all']), Tree('NP', [Tree('ADJ', ['final']), Tree('N', ['results']), Tree('PP', [Tree('P', ['in']), Tree('NP', [Tree('DT', ['a']), Tree('N', ['Word_Document'])])])])])])]

现在让我们来看一下present all intermediate and final results in a Word_Document的连词:

Now let's go for the conjunctions for present all intermediate and final results in a Word_Document:

import nltk

your_grammar = nltk.CFG.fromstring("""
S -> V NP
V -> 'describe' | 'present'
NP -> PRP N | DT N PP | DT N | ADJ N PP | DT NP
PRP -> 'your'
N -> 'work' | 'step' | 'results' | 'Word_Document'
PP -> P NP
P -> 'of' | 'in'
DT -> 'every' | 'a' | 'all'
ADJ -> 'final' | 'intermediate' | ADJ CONJ ADJ
CONJ -> 'and'
""")

parser = nltk.ChartParser(your_grammar)
#sent = 'describe every step of your work'.split()
sent = 'present all intermediate and final results in a Word_Document'.split()
print (list(parser.parse(sent)))

[输出]:

[Tree('S', [Tree('V', ['present']), Tree('NP', [Tree('DT', ['all']), Tree('NP', [Tree('ADJ', [Tree('ADJ', ['intermediate']), Tree('CONJ', ['and']), Tree('ADJ', ['final'])]), Tree('N', ['results']), Tree('PP', [Tree('P', ['in']), Tree('NP', [Tree('DT', ['a']), Tree('N', ['Word_Document'])])])])])])]

但这只会给您一个阅读present all [(intermediate and final) (results) (in a Word_Document)].对于模棱两可的结果，我将留给您想象； P

But that only give you one reading present all [(intermediate and final) (results) (in a Word_Document)]. For ambiguous results, I'll leave it to your imagination ;P

现在让我们继续并连接S -> S CONJ S到describe your work and present all intermediate and final results in a Word_Document:

Now let's move on and concatenate the S -> S CONJ S for describe your work and present all intermediate and final results in a Word_Document:

import nltk

your_grammar = nltk.CFG.fromstring("""
S -> V NP | S CONJ S
V -> 'describe' | 'present'
NP -> PRP N | DT N PP | DT N | ADJ N PP | DT NP
PRP -> 'your' 
N -> 'work' | 'step' | 'results' | 'Word_Document'
PP -> P NP
P -> 'of' | 'in'
DT -> 'every' | 'a' | 'all'
ADJ -> 'final' | 'intermediate' | ADJ CONJ ADJ
CONJ -> 'and'
""")

parser = nltk.ChartParser(your_grammar)
sent1 = 'describe every step of your work'
sent2 = 'present all intermediate and final results in a Word_Document'
sent = ' and '.join([sent1, sent2]).split()
print (list(parser.parse(sent)))

[输出]:

[Tree('S', [Tree('S', [Tree('V', ['describe']), Tree('NP', [Tree('DT', ['every']), Tree('N', ['step']), Tree('PP', [Tree('P', ['of']), Tree('NP', [Tree('PRP', ['your']), Tree('N', ['work'])])])])]), Tree('CONJ', ['and']), Tree('S', [Tree('V', ['present']), Tree('NP', [Tree('DT', ['all']), Tree('NP', [Tree('ADJ', [Tree('ADJ', ['intermediate']), Tree('CONJ', ['and']), Tree('ADJ', ['final'])]), Tree('N', ['results']), Tree('PP', [Tree('P', ['in']), Tree('NP', [Tree('DT', ['a']), Tree('N', ['Word_Document'])])])])])])])]

肯定有其他方法可以编写适合您句子的CFG语法，这只是众多方法之一.但一般来说，将CFG语法写成bitesize.

There're surely other ways to write the CFG grammar to suit your sentence and this is just one of the many ways. But in general, write the CFG grammar in bitesize.

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