朴素贝叶斯算法的python实现
发布时间:2020-12-17 17:27:31 所属栏目:Python 来源:网络整理
导读:今天PHP站长网 52php.cn把收集自互联网的代码分享给大家,仅供参考。 #coding=utf-8from numpy import *def loadDataSet(): postingList=[['my','dog','has','flea','problems','help','please'],['maybe','not','take','
以下代码由PHP站长网 52php.cn收集自互联网 现在PHP站长网小编把它分享给大家,仅供参考 #coding=utf-8 from numpy import * def loadDataSet(): postingList=[['my','dog','has','flea','problems','help','please'],['maybe','not','take','him','to','park','stupid'],['my','dalmation','is','so','cute','I','love','him'],['stop','posting','stupid','worthless','garbage'],['mr','licks','ate','my','steak','how','stop',['quit','buying','food','stupid']] classVec = [0,1,1] #1 is abusive,0 not return postingList,classVec #创建一个带有所有单词的列表 def createVocabList(dataSet): vocabSet = set([]) for document in dataSet: vocabSet = vocabSet | set(document) return list(vocabSet) def setOfWords2Vec(vocabList,inputSet): retVocabList = [0] * len(vocabList) for word in inputSet: if word in vocabList: retVocabList[vocabList.index(word)] = 1 else: print 'word ',word,'not in dict' return retVocabList #另一种模型 def bagOfWords2VecMN(vocabList,inputSet): returnVec = [0]*len(vocabList) for word in inputSet: if word in vocabList: returnVec[vocabList.index(word)] += 1 return returnVec def trainNB0(trainMatrix,trainCatergory): numTrainDoc = len(trainMatrix) numWords = len(trainMatrix[0]) pAbusive = sum(trainCatergory)/float(numTrainDoc) #防止多个概率的成绩当中的一个为0 p0Num = ones(numWords) p1Num = ones(numWords) p0Denom = 2.0 p1Denom = 2.0 for i in range(numTrainDoc): if trainCatergory[i] == 1: p1Num +=trainMatrix[i] p1Denom += sum(trainMatrix[i]) else: p0Num +=trainMatrix[i] p0Denom += sum(trainMatrix[i]) p1Vect = log(p1Num/p1Denom)#处于精度的考虑,否则很可能到限归零 p0Vect = log(p0Num/p0Denom) return p0Vect,p1Vect,pAbusive def classifyNB(vec2Classify,p0Vec,p1Vec,pClass1): p1 = sum(vec2Classify * p1Vec) + log(pClass1) #element-wise mult p0 = sum(vec2Classify * p0Vec) + log(1.0 - pClass1) if p1 > p0: return 1 else: return 0 def testingNB(): listOPosts,listClasses = loadDataSet() myVocabList = createVocabList(listOPosts) trainMat=[] for postinDoc in listOPosts: trainMat.append(setOfWords2Vec(myVocabList,postinDoc)) p0V,p1V,pAb = trainNB0(array(trainMat),array(listClasses)) testEntry = ['love','dalmation'] thisDoc = array(setOfWords2Vec(myVocabList,testEntry)) print testEntry,'classified as: ',classifyNB(thisDoc,p0V,pAb) testEntry = ['stupid','garbage'] thisDoc = array(setOfWords2Vec(myVocabList,pAb) def main(): testingNB() if __name__ == '__main__': main() 以上内容由PHP站长网【52php.cn】收集整理供大家参考研究 如果以上内容对您有帮助,欢迎收藏、点赞、推荐、分享。 (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |