nlp - 将 TF-IDF 与预训练的 Word 嵌入相结合

Question

我有一个网站元描述列表(128k 描述；每个描述平均 20-30 个字)，并且我正在尝试建立一个相似度排名器(如:向我展示与此站点元描述最相似的 5 个站点)
它与 TF-IDF uni- 和 bigram 配合得非常好 ，我认为我可以通过添加预先训练的词嵌入来进一步改进它(准确地说是 spacy “en_core_web_lg”)。 情节扭曲:它根本不起作用 .字面上没有得到一个好的猜测，它突然吐出完全随机的建议。
下面是我的代码。关于我可能出错的地方有什么想法吗？我是否在监督一些非常直观的事情？

import numpy as np
from sklearn.feature_extraction.text import TfidfVectorizer
import sys
import pickle
import spacy
import scipy.sparse
from scipy.sparse import csr_matrix
import math
from sklearn.metrics.pairwise import linear_kernel
nlp=spacy.load('en_core_web_lg')


""" Tokenizing"""
def _keep_token(t):
    return (t.is_alpha and 
            not (t.is_space or t.is_punct or 
                 t.is_stop or t.like_num))
def _lemmatize_doc(doc):
    return [ t.lemma_ for t in doc if _keep_token(t)]

def _preprocess(doc_list):     
    return [_lemmatize_doc(nlp(doc)) for doc in doc_list]
def dummy_fun(doc):
    return doc

# Importing List of 128.000 Metadescriptions:
Web_data=open("./data/meta_descriptions","r", encoding="utf-8")
All_lines=Web_data.readlines()
# outputs a list of meta-descriptions consisting of lists of preprocessed tokens:
data=_preprocess(All_lines) 

# TF-IDF Vectorizer:    
vectorizer = TfidfVectorizer(min_df=10,tokenizer=dummy_fun,preprocessor=dummy_fun,)
    tfidf = vectorizer.fit_transform(data)    
dictionary = vectorizer.get_feature_names()

# Retrieving Word embedding vectors:
temp_array=[nlp(dictionary[i]).vector for i in range(len(dictionary))]

# I had to build the sparse array in several steps due to RAM constraints
# (with bigrams the vocabulary gets as large as >1m 
dict_emb_sparse=scipy.sparse.csr_matrix(temp_array[0])
for arr in range(1,len(temp_array),100000):
    print(str(arr))        
    dict_emb_sparse=scipy.sparse.vstack([dict_emb_sparse, scipy.sparse.csr_matrix(temp_array[arr:min(arr+100000,len(temp_array))])])

# Multiplying the TF-IDF matrix with the Word embeddings: 
tfidf_emb_sparse=tfidf.dot(dict_emb_sparse)

# Translating the Query into the TF-IDF matrix and multiplying with the same Word Embeddings:
query_doc= vectorizer.transform(_preprocess(["World of Books is one of the largest online sellers of second-hand books in the world Our massive collection of over million cheap used books also comes with free delivery in the UK Whether it s the latest book release fiction or non-fiction we have what you are looking for"]))
query_emb_sparse=query_doc.dot(dict_emb_sparse)

# Calculating Cosine Similarities:
cosine_similarities = linear_kernel(query_emb_sparse, tfidf_emb_sparse).flatten()

related_docs_indices = cosine_similarities.argsort()[:-10:-1]

# Printing the Site descriptions with the highest match:    
for ID in related_docs_indices:
    print(All_lines[ID])

我从 this Github 窃取了部分代码/逻辑代表
有人在这里看到任何直接的错误吗？
非常感谢!!

Answer 1

你应该尝试训练嵌入到你自己的语料库中。有很多包:gensim，手套。
您可以使用来自 BERT 的嵌入，而无需在您自己的语料库上重新训练。

你应该知道不同语料上的概率分布总是不同的。例如，关于食物的帖子中“篮球”的数量与体育新闻中的术语数量非常不同，因此在这些语料库中“篮球”的词嵌入差距很大。