机器学习之-朴素贝叶斯简单实例

import numpy as np
import math

#加载模拟数据
def loaddata():
    postingList=[['my','dog','has','flea','problem','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  0 非侮辱
    return postingList,classVec

#创建词汇表
def createSet(dataset):
    result = set([])
    for i in dataset:
        result = result | set(i)
    return list(result)

# dataSet,labels = loaddata()
# vacablist = createSet(dataSet)
# print('外lables',labels)
# print('外dataSet',dataSet)
# print('外vacablist:',vacablist)

#创建和词汇表对应的向量
def setofword(vacablist,inputdata):
    mylist = [0] * len(vacablist)
    for word in inputdata:
       if word in vacablist:
           mylist[vacablist.index(word)] = 1
       else:
           print('没有 {} 这个词'.format(word))
    return mylist
# setofdata = setofword(vacablist,dataSet[3])
# print('外setofdata:',setofdata)                        #[1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0]
# print(vacablist)                        #['garbage', 'to', 'worthless', 'ate', 'has', 'so', 'take', 'cute', 'dog', 'flea', 'buying', 'help', 'is', 'park', 'I', 'food', 'my', 'licks', 'posting', 'dalmation', 'problem', 'please', 'stop', 'how', 'stupid', 'maybe', 'love', 'steak', 'quit', 'him', 'not', 'mr']
# print(dataSet[3])                       #['stop', 'posting', 'stupid', 'worthless', 'garbage']
# trainmat = []
# for i in dataSet:
#     trainmat.append(setofword(vacablist,i))
# print('外trainmat:',trainmat)

# 训练函数，算P(word\1)的概率
def P1(trainmat,labels):
    plable_1 = sum(labels)/len(labels)
    data_0 = np.ones(len(trainmat[0]))
    count_0 = 2
    data_1 = np.ones(len(trainmat[0]))
    count_1 = 2
    for i in range(len(labels)):
        if labels[i] == 0:
            data_0 += trainmat[i]
            count_0 += sum(trainmat[i])
        if labels[i] == 1:
            data_1 += trainmat[i]
            count_1 += sum(trainmat[i])

    data_0 = data_0 / count_0
    data_1 = data_1/count_1
    print('data_0:{},count:{}'.format(data_0,count_0))
    print('data_1:{},count:{}'.format(data_1, count_1))
    print('plabel_1:',plable_1)
    return  data_0,data_1,plable_1

# P1(trainmat,labels)
#用得到的概率分类
def classfy(testset,data_0,data_1,plabel_1):
    print('开始classfy')
    p1 = 1
    p0 = 1
    for i in range(len(testset)):
        if testset[i] ==1 :
            p1 = p1 * data_1[i]
            p0 = p0 * data_0[i]
    p1 = p1 * plabel_1
    p0 = p0 * (1-plabel_1)
    print('p1:{},p0:{}'.format(p1,p0))
    if p1>p0:
        print('该分类为1')
        return 1
    else:
        print('该分类为0')
        return 0

#测试总逻辑代码
def test():
    dataSet,labels = loaddata()
    vacablist = createSet(dataSet)
    trainmat = []
    for i in dataSet:                                   #因为训练函数需要训练数据是词汇表的格式
        trainmat.append(setofword(vacablist,i))
    data_0, data_1, plable_1 = P1(trainmat,labels)
    testlist = ['my','love','stupid']
    testdata = setofword(vacablist,testlist)
    classfy(testdata,data_0,data_1,plable_1)

test()