1. 读邮件数据集文件,提取邮件本身与标签。
列表
numpy数组
2.邮件预处理
- 邮件分句
- 句子分词
- 大小写,标点符号,去掉过短的单词
- 词性还原:复数、时态、比较级
- 连接成字符串
2.1 传统方法来实现
2.2 nltk库的安装与使用
pip install nltk
import nltk
nltk.download() # sever地址改成 http://www.nltk.org/nltk_data/
或
https://github.com/nltk/nltk_data下载gh-pages分支,里面的Packages就是我们要的资源。
将Packages文件夹改名为nltk_data。
或
网盘链接:https://pan.baidu.com/s/1iJGCrz4fW3uYpuquB5jbew 提取码:o5ea
放在用户目录。
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安装完成,通过下述命令可查看nltk版本:
import nltk
print nltk.__doc__
2.1 nltk库 分词
nltk.sent_tokenize(text) #对文本按照句子进行分割
nltk.word_tokenize(sent) #对句子进行分词
2.2 punkt 停用词
from nltk.corpus import stopwords
stops=stopwords.words('english')
*如果提示需要下载punkt
nltk.download(‘punkt’)
或 下载punkt.zip
https://pan.baidu.com/s/1OwLB0O8fBWkdLx8VJ-9uNQ 密码:mema
复制到对应的失败的目录C:UsersAdministratorAppDataRoaming ltk_data okenizers并解压。
2.3 NLTK 词性标注
nltk.pos_tag(tokens)
2.4 Lemmatisation(词性还原)
from nltk.stem import WordNetLemmatizer
lemmatizer = WordNetLemmatizer()
lemmatizer.lemmatize('leaves') #缺省名词
lemmatizer.lemmatize('best',pos='a')
lemmatizer.lemmatize('made',pos='v')
一般先要分词、词性标注,再按词性做词性还原。
2.5 编写预处理函数
def preprocessing(text):
sms_data.append(preprocessing(line[1])) #对每封邮件做预处理
3. 训练集与测试集
4. 词向量
5. 模型
代码:
import numpy as np
def loadDataSet():
postingList = [
['my','dog','has','flea','problems','help','please'],
['maybe','not','take','him','to','dog','park','stupid'],
['my','dalmation','is','so','cute','I','love','him'],
['stop','posting','stupid','worthless','garbage'],
['mr','licks','ate','my','steak','how','to','stop','him'],
['quit','buying','worthless','dog','food','stupid']
]
classVec = [0,1,0,1,0,1] #1:侮辱性文字,0:正常言论
return postingList,classVec
def createVocabList(dataSet):
vocabSet = set([]) #创建一个空集
for document in dataSet:
vocabSet = vocabSet | set(document) #创建两个集合的并集,去重操作
return list(vocabSet)
def setOfWords2Vec(vocabList,inputSet): #对单词做简单的词向量
returnVec = [0] * len(vocabList)
for word in inputSet:
if word in vocabList:
returnVec[vocabList.index(word)] = 1
else:
print ("the word: %s is not in my Vocabulary!" % word)
return returnVec
#训练函数
def trainNB0(trainMatrix,trainCategory):
#trainMatrix : 0,1表示的文档矩阵
#trainCategory : 类别标签构成的向量
numTrainDocs = len(trainMatrix)
numWords = len(trainMatrix[0])
pAbusive = sum(trainCategory) / float(numTrainDocs) #P(c1)
p0Num = np.zeros(numWords)
p1Num = np.zeros(numWords)
p0Denom = 0.0
p1Denom = 0.0
#len(trainMatrix) == len(trainCategory)
for i in range(numTrainDocs):
if trainCategory[i] == 1:
p1Num += trainMatrix[i]
p1Denom += sum(trainMatrix[i])
else:
p0Num += trainMatrix[i]
p0Denom += sum(trainMatrix[i])
p0Vect = p0Num / p0Denom #P(Wi|C1)的向量形式
p1Vect = p1Num / p1Denom #p(wi|c2)的向量形式
return p0Vect,p1Vect,pAbusive
listPosts,listClasses = loadDataSet()
myVocabList = createVocabList(listPosts)
trainMat = []
for postinDoc in listPosts:
trainMat.append(setOfWords2Vec(myVocabList,postinDoc))
print (trainMat)
p0V,p1V,pAb = trainNB0(trainMat,listClasses)
print ("p0V:
",p0V)
print ("p1V:
",p1V)
print ("pAb:
",pAb)
运行结果: