深度学习语言模型(2)-词向量，神经概率网络模型(keras版本)

心已赠人 2022-05-12 11:28 215阅读 0赞

目录:  
[深度学习语言模型(1)-word2vce的发展历程][1_-word2vce]  
[深度学习语言模型(2)-词向量，神经概率网络模型(keras版本)][2_-_keras]  
[深度学习语言模型(3)-word2vce负采样(Negative Sampling) 模型(keras版本)][3_-word2vce_Negative Sampling_ _keras]

1.神经概率网络模型(2003年)，步骤如下:  
（1）输入层，将每一个词都使用随机的100维向量表示  
（2）投影层，将一个上下文的词拼接起来，比如滑动窗口是3，则有(batch\_size,6,100)  
（3）隐藏层，就是一个全连接层，比如(100,1024)  
（4）输出层，使用softmax分类器，类别就是所有词的id,比如现在有50000个词，则，输出层(1024,50000)  
在反向传播过程中，不仅更新输出层，隐藏层的权重，还要更新投影层中的x,即词相对应的100维向量。  
优点:  
（1）即使两个句子出现的次数由很大悬殊，但相似的句子会几乎被同等对待，比如”我今天打篮球”和”我今天打羽毛球”。但还是由点差别，差别来自于两句子中的篮球和羽毛球出现不等，因为在训练过程中训练篮球时，羽毛球的label=0，在训练羽毛球时，篮球的label=0，所以会收到次数的影响，如果不想受到次数的影响，则可以采用将在训练篮球的时候，羽毛球的label=1,训练羽毛球的时候，篮球的label=1。或者采用word2vec（Hierarchical Softmax）模型或者word2vec （Negative Sampling）模型，在训练充足的情况下差距会变小。  
缺点:  
（1）如果词的量过大，后面的输出层权重参数过多，导致内存不足

# coding=utf-8 ''' Created on 2018年9月15日 @author: admin ''' from gensim import corpora, models, similarities import numpy as np if __name__ == '__main__': text = [["我","今天","打","篮球"], ["我","今天","打","足球"], ["我","今天","打","羽毛球"], ["我","今天","打","网球"], ["我","今天","打","排球"], ["我","今天","打","气球"], ["我","今天","打","游戏"], ["我","今天","打","冰球"], ["我","今天","打","人"], ["我","今天","打","台球"], ["我","今天","打","桌球"], ["我","今天","打","水"], ["我","今天","打","篮球"], ["我","今天","打","足球"], ["我","今天","打","羽毛球"], ["我","今天","打","网球"], ["我","今天","打","排球"], ["我","今天","打","气球"], ] #使用gensim生成词典 dictionary = corpora.Dictionary(text,prune_at=2000000) #打印词典中的词 for key in dictionary.iterkeys(): print(key,dictionary.get(key),dictionary.dfs[key]) #保存词典 dictionary.save_as_text('word_dict.dict', sort_by_word=True) #加载词典 dictionary = dictionary.load_from_text('word_dict.dict') #词语个数 word_num = len(dictionary.keys()) #使用多少编文章生成每个batch数据 sentence_batch_size = 1 #滑动窗口 window = 3 #生成CBOW数据 def data_generator(): #训练数据生成器 while True: x,y = [],[] _ = 0 for sentence in text: #在两端插入空字符，这里使用word_num这个值来代替 sentence = [word_num]*window + [dictionary.token2id[w] for w in sentence if w in dictionary.token2id] + [word_num]*window for i in range(window, len(sentence)-window): x.append(sentence[i-window:i]+sentence[i+1:i+1+window]) #因为使用的loss函数为sparse_categorical_crossentropy，所以不用one-hot y.append([sentence[i]]) _ += 1 if _ == sentence_batch_size: x,y = np.array(x),np.array(y) print("输入的数据 :",x.shape) print("对应的标签 :",y.shape) yield x,y x,y = [],[] _ = 0 from keras.models import Sequential from keras.layers import Dense, Activation,Embedding,Reshape model = Sequential() model.add(Embedding(word_num+1, 200, input_length=6)) model.add(Dense(1024, activation='relu')) model.add(Flatten()) model.add(Dense(word_num+1, activation='softmax')) model.compile(optimizer='sgd', loss='sparse_categorical_crossentropy', metrics=['accuracy']) model.summary() model.fit_generator(data_generator(),steps_per_epoch =np.ceil(dictionary.num_docs/sentence_batch_size),epochs=1000,max_queue_size=1,workers=1) #保存模型 model.save_weights("DNNword-vec.h5") #加载模型 model.load_weights("DNNword-vec.h5",by_name=True) #获取embeding的权重，也就是词向量 embeddings = model.get_weights()[0] #向量标准化 normalized_embeddings = embeddings / (embeddings**2).sum(axis=1).reshape((-1,1))**0.5 dictionary.id2token = { j:i for i,j in dictionary.token2id.items()} #获取前面最相似的10个词语 def most_similar(w,dictionary): v = normalized_embeddings[dictionary.token2id[w]] #向量标准化之后分母就是1，所以直接相乘就好 sims = np.dot(normalized_embeddings, v) sort = sims.argsort()[::-1] sort = sort[sort > 0] #如果是占位符则不输出 return [(dictionary.id2token[i],sims[i]) for i in sort[:10] if i in dictionary.id2token] for sim in most_similar(u'网球',dictionary): print(sim[0],sim[1]) # 网球 1.0000001 # 羽毛球 0.11263792 # 桌球 0.07463527 # 篮球 0.066648 # 足球 0.06379064 # 台球 0.046809338 # 排球 0.04252596 # 我 0.04014937 # 人 0.028555304 # 水 0.007580313

[1_-word2vce]: https://blog.csdn.net/u011311291/article/details/82744618
[2_-_keras]: https://blog.csdn.net/u011311291/article/details/82745240
[3_-word2vce_Negative Sampling_ _keras]: https://blog.csdn.net/u011311291/article/details/82778490