def exercise9():
#Design at least 5 features and explain them. Use nltk.NaiveBayesClassifier.
#Report the accuracy of your classifier built using all of the features that you designed.
#Use show_most_inforamtive_feautures(5) functionality from the classifier to inspect the individual feature performance.
#Which of your features seem to be most influential?
print('Extra Credit')
from nltk.corpus import ppattach
training_ppattach_corpus = ppattach.attachments('training')
noun_ppattach_corpus = [inst for inst in training_ppattach_corpus if inst.attachment == 'N']
features = [(noun_features(inst), inst.prep) for inst in noun_ppattach_corpus]
cutoff = int(len(features) / 4)
train_set, test_set = features[:cutoff], features[cutoff:]
# Naive Bayes Classifier
classifier1 = nltk.NaiveBayesClassifier.train(train_set)
#Decision Tree Classifier
classifier2 = nltk.DecisionTreeClassifier.train(train_set)
print("Naive Bayes classifier")
print("Accuracy", nltk.classify.accuracy(classifier1, test_set))
print("team", classifier1.classify({'noun1': 'team'}), "researchers")
print("Decision Tree classifier")
print("Accuracy", nltk.classify.accuracy(classifier2, test_set))
print("team", classifier2.classify({'noun1': 'team'}), "researchers")
print("5 features:")
print classifier1.show_most_informative_features(5)
def exercise9():
print('Extra Credit')
from nltk.corpus import ppattach
training_ppattach_corpus = ppattach.attachments('training')
noun_ppattach_corpus = [
inst for inst in training_ppattach_corpus if inst.attachment == 'N'
]
features = [(noun_features(inst), inst.prep)
for inst in noun_ppattach_corpus]
cutoff = int(len(features) / 4)
train_set, test_set = features[:cutoff], features[cutoff:]
# Naive Bayes Classifier
classifier1 = nltk.NaiveBayesClassifier.train(train_set)
# Decision Tree Classifier
classifier2 = nltk.DecisionTreeClassifier.train(train_set)
print("Naive Bayes classifier")
print("Accuracy", nltk.classify.accuracy(classifier1, test_set))
print("team", classifier1.classify({'noun1': 'team'}), "researchers")
print("Decision Tree classifier")
print("Accuracy", nltk.classify.accuracy(classifier2, test_set))
print("team", classifier2.classify({'noun1': 'team'}), "researchers")
print("5 features:")
print(classifier1.show_most_informative_features(5))
def exercise9():
print('Extra Credit')
featuresets = [(ppattach_features(ppobject.noun1, ppobject.noun2,
ppobject.verb), ppobject.prep)
for ppobject in ppattach.attachments('training')
if ppobject.attachment == 'N']
train_set, test_set = featuresets[100:], featuresets[:100]
classifier = nltk.NaiveBayesClassifier.train(train_set)
print(nltk.classify.accuracy(classifier, test_set))
print(classifier.most_informative_features(5))
lk[i]=""
tk=tuple(lk)
lv=list(value)
lv[i]=""
tv=tuple(lv)
assert tk not in feats
feats[tk]=tv
return feats
def get_list_of_feats_lables(data):
# data_tuples=[(ppa,ppa.attachment) for ppa in data]
# feat_lable_tuples=nltk.classify.apply_features(get_feats,data)
feat_lable_tuples=[(get_feats(ppa),ppa.attachment) for ppa in data]
return feat_lable_tuples
# print "Train"
train_set = [ (get_feats(item), item.attachment) for item in ppattach.attachments('training') ]
# print "Dev"
dev_set = [ (get_feats(item), item.attachment) for item in ppattach.attachments('devset') ]
# print "Test"
test_set = [ (get_feats(item), item.attachment) for item in ppattach.attachments('test') ]
# print "Done"
# train_feats_labels=get_list_of_feats_lables(train_set)
# dev_feats_labels=get_list_of_feats_lables(dev_set)
# test_feats_labels=get_list_of_feats_lables(test_set)
classifier=nltk.NaiveBayesClassifier.train(train_set) #Not sure how to smooth this!
devacc = nltk.classify.accuracy(classifier, dev_set)
testacc = nltk.classify.accuracy(classifier, test_set)
#!/usr/bin/env python
# -*-coding:utf-8 -*-
'''
9. PP附件语料库是描述介词短语附着决策的语料库。
语料库中的每个实例被编码为
PP Attachment对象：
使用此子语料库，建立一个分类器，尝试预测哪些介词是用来连接一对给定的名词。
例如：给定的名词对team 和 researchers，分类器应该预测出介词 of。
更多的使用 PP 附件语料库的信息，参阅http://www.nltk.org/howto 上的语料库HOWTO。
'''
from nltk.corpus import ppattach
import nltk
ppattach.attachments('training')
inst = ppattach.attachments('training')[2]
print inst
print inst.noun1, inst.prep, inst.noun2
#根据PPAttachment的特征，将字典项作为特征项录入，将prep作为结果项，直接生成分类器所需的set
def gender_features(NounAndPrep):
return ({
'noun1': NounAndPrep.noun1,
'noun2': NounAndPrep.noun2,
'sent': NounAndPrep.sent,
'verb': NounAndPrep.verb,
'attachment': NounAndPrep.attachment
}, NounAndPrep.prep)
print gender_features(inst)
default_label = 'N'
def classify(self, featureset):
return self.default_label
def default_feature(item):
return {
'verb': item.verb,
'prep': item.prep,
'noun1+verb': (item.noun1, item.verb),
'noun1+prep': (item.noun1, item.prep),
'verb+prep': (item.verb, item.prep),
'verb+prep+noun2': (item.verb, item.prep, item.noun2),
'verb+prep+noun1': (item.verb, item.prep, item.noun1),
'prep+noun2': (item.prep, item.noun2),
#'noun1+noun2+prep': (item.noun1, item.noun2, item.prep),
}
train_set = [ (default_feature(item), item.attachment) for item in ppattach.attachments('training') ]
# the dev_set is like the open book exam; while the test_set is like the close book exam
dev_set = [ (default_feature(item), item.attachment) for item in ppattach.attachments('devset') ]
test_set = [ (default_feature(item), item.attachment) for item in ppattach.attachments('test') ]
#classifier = DefaultClassifier()
classifier = nltk.NaiveBayesClassifier.train(train_set)
devacc = nltk.classify.accuracy(classifier, dev_set)
testacc = nltk.classify.accuracy(classifier, test_set)
print "all:dev:%lf" % (devacc)
print "all:test:%lf" % (testacc)
import nltk
from nltk.corpus import ppattach
import sys
class DefaultClassifier(nltk.classify.ClassifierI):
default_label = 'N'
def classify(self, featureset):
return self.default_label
def default_feature(item):
return {'None': None}
train_set = [(default_feature(item), item.attachment)
for item in ppattach.attachments('training')]
dev_set = [(default_feature(item), item.attachment)
for item in ppattach.attachments('devset')]
test_set = [(default_feature(item), item.attachment)
for item in ppattach.attachments('test')]
classifier = DefaultClassifier()
devacc = nltk.classify.accuracy(classifier, dev_set)
testacc = nltk.classify.accuracy(classifier, test_set)
print "prep:dev:%lf" % (devacc)
print "prep:test:%lf" % (testacc)
#!/usr/bin/python
# -*- coding: utf-8 -*-
from nltk.corpus import ppattach
print(ppattach.attachments('training')) # doctest: +NORMALIZE_WHITESPACE
inst = ppattach.attachments('training')[0]
print(inst.sent, inst.verb, inst.noun1, inst.prep, inst.noun2)
print(inst.attachment)
def dummy_print():
[
print(ppobject.noun1, ppobject.prep, ppobject.noun2, ppobject.verb)
for ppobject in ppattach.attachments('training')
if ppobject.attachment == 'N'
]
import nltk
from nltk.corpus import ppattach
from pickle import dump
ppattach.attachments('training')
inst = ppattach.attachments('training')[2]
print(inst)
print((inst.noun1, inst.prep, inst.noun2))
def noun_features(inst):
return {
'noun1': inst.noun1,
'noun2': inst.noun2,
'pos1': nltk.pos_tag(inst.noun1),
'pos2': nltk.pos_tag(inst.noun2),
}
nattach = [({
'noun1': inst.noun1,
'noun2': inst.noun2
}, inst.prep) for inst in ppattach.attachments('training')
if inst.attachment == 'N']
size = int(0.1 * len(nattach))
train_set, test_set = nattach[size:], nattach[:size]
# classifier = nltk.MaxentClassifier.train(train_set)
classifier = nltk.NaiveBayesClassifier.train(train_set)
print(nltk.classify.accuracy(classifier, test_set))
from nltk.corpus import ppattach
print ppattach.attachments('training')[0]
print ppattach.attachments('devset')[0]
print ppattach.attachments('test')[0]
def exercise0():
documents = [(list(movie_reviews.words(fileid)), category)
for category in movie_reviews.categories()
for fileid in movie_reviews.fileids(category)]
featuresets = [(document_features_ex0(d), c) for (d, c) in documents]
train_set, test_set = featuresets[100:], featuresets[:100]
classifier = nltk.NaiveBayesClassifier.train(train_set)
print("Accuracy : ", nltk.classify.accuracy(classifier, test_set))
print("Most Informative Features : ")
print(classifier.most_informative_features(5))
nattach = [
inst for inst in ppattach.attachments('training') if inst.attachment == 'N'
]
def features(noun1, noun2, verb):
feature_set = {}
feature_set['noun1_suffix'] = noun1[-1:].lower()
feature_set['noun2_suffix'] = noun2[-1:].lower()
feature_set['noun1_prefix'] = noun1[0:3].lower()
feature_set['noun2_prefix'] = noun2[0:3].lower()
feature_set['verb'] = verb.lower()
if feature_set['noun1_suffix'] == feature_set['noun2_suffix']:
feature_set['special1'] = True
else:
feature_set['special1'] = False
import nltk
from nltk.corpus import ppattach
def pp_features(pp):
return {'noun1': pp.noun1, 'noun2': pp.noun2}
phrases = [pp for pp in ppattach.attachments('training') if pp.attachment == 'N']
featuresets = [(pp_features(pp), pp.prep) for pp in phrases]
train_set, test_set = featuresets[1000:], featuresets[:1000]
classifier = nltk.NaiveBayesClassifier.train(train_set)
print(nltk.classify.accuracy(classifier, test_set))
print(classifier.show_most_informative_features(10))
classifier = nltk.MaxentClassifier.train(train_set)
print(nltk.classify.accuracy(classifier, test_set))
print(classifier.show_most_informative_features(10))
