简介

Word2Vec 学习（Skip-gram方法）
参考资料：https://wmathor.com/index.php/archives/1443/

代码

import torch
import numpy as np 
import unicodedata
import string
import re
import torch.nn as nn
import torch.optim as optim
import torch.utils.data as data

字典库

class Dictionary:
    def __init__(self, name):
        self.name=name
        self.words=[]
    
    def addWord(self, word):
        if word not in self.words:
            self.words.append(word)
    
    def getSize(self):
        return len(self.words)

字符串转换函数，可去除标点符号，统一为小写
（参照pytorch中文文档教程）


def unicodeToAscii(s):
    return ''.join(
        c for c in unicodedata.normalize('NFD', s)
        if unicodedata.category(c) != 'Mn'
    )

def normalizeString(s):
    s = unicodeToAscii(s.lower())
    s = re.sub(r"([.!?])", r" ", s)
    s = re.sub(r"[^a-zA-Z.!?]+", r" ", s)
    s=s.strip()
    return s

从文件中读取字符串

lines=[]
with open('data\\news.txt',encoding='utf-8') as f:
    phrases=f.read().strip().split('\n')
    for phrase in phrases:
        phrase=phrase.strip().split('.')
        for p in phrase:
            if p!='':
                lines+=normalizeString(p).split(' ')

建立中心/上下文词对

engDictionary=Dictionary('English')
for word in lines:
    engDictionary.addWord(word)

def make_list(lines):
    words_list=[]
    for i in range(2, len(lines)-2):
        centre=engDictionary.words.index(lines[i])
        context=[]
        for t in range(i-2, i+3):
            if t!=i:
                context.append(engDictionary.words.index(lines[t]))
        for w in context:
            words_list.append([centre, w])
    return words_list
 
words_list=make_list(lines)

转换为训练数据
ps: 在造one-hot向量时要用numpy的narray，直接用torch.tensor会报错

input_data=[]
output_data=[]

def make_data(words_list):
    for w in words_list:
        k=np.zeros(engDictionary.getSize())
        k[w[0]]=1
        input_data.append(k)
        output_data.append(w[1])

make_data(words_list)

input_data=torch.Tensor(input_data)
output_data=torch.LongTensor(output_data)

dataset=data.TensorDataset(input_data, output_data)
dataloader=data.DataLoader(dataset, batch_size=8, shuffle=True)

模型
ps: 最后不需要softmax，crossentropy自带softmax

class Skip_gram(nn.Module):
    def __init__(self, input_size, hidden_size):
        super(Skip_gram, self).__init__()
        self.hidden_size=hidden_size
        self.W=nn.Linear(input_size, hidden_size, bias=False)
        self.V=nn.Linear(hidden_size, input_size, bias=False)
        
    def forward(self, x):
        x=self.W(x)
        x=self.V(x)
        return x
    
model=Skip_gram(engDictionary.getSize(), 10)

训练
ps: 1. optimizer用Adam，不用SGD
2. crossentropy的输入一个为概率向量，另一个为分类标签的值，不是向量

criterion=nn.CrossEntropyLoss()
optimizer=optim.Adam(model.parameters(), lr=0.001)

def train(epoches):
    for epoch in range(1, epoches+1):
        sumloss=0
        for x, y in iter(dataloader):
            optimizer.zero_grad()
            o=model(x)
            loss=criterion(o, y)
            sumloss+=loss.item()
            loss.backward()
            optimizer.step()
        if epoch%100==0:
            print('epoch {}: loss:{:.2f}'.format(epoch, sumloss))

train(1000)

保存网络数据

PATH='./word2vec.pth'
torch.save(model.state_dict(), PATH)

本文地址：https://blog.csdn.net/qq_32401661/article/details/109960321

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