如何实现Python底层技术的自然语言处理

import re
import nltk
from nltk.corpus import stopwords
from nltk.tokenize import word_tokenize

def preprocess_text(text):
    # 去除标点符号
    text = re.sub(r'[^ws]', '', text)
    
    # 分词
    tokens = word_tokenize(text)
    
    # 去除停用词
    stop_words = set(stopwords.words('english'))
    tokens = [token for token in tokens if token.lower() not in stop_words]
    
    # 返回处理后的文本
    return tokens

import nltk
from nltk.tokenize import word_tokenize
from nltk.tag import pos_tag

def pos_tagging(text):
    # 分词
    tokens = word_tokenize(text)
    
    # 词性标注
    tagged_tokens = pos_tag(tokens)
    
    # 返回标注结果
    return tagged_tokens

import nltk
from nltk.tokenize import word_tokenize
from nltk.chunk import ne_chunk

def named_entity_recognition(text):
    # 分词
    tokens = word_tokenize(text)
    
    # 命名实体识别
    tagged_tokens = pos_tag(tokens)
    named_entities = ne_chunk(tagged_tokens)
    
    # 返回识别结果
    return named_entities

import nltk
from nltk.corpus import movie_reviews
from nltk.tokenize import word_tokenize
from nltk.classify import NaiveBayesClassifier
from nltk.classify.util import accuracy

def text_classification(text):
    # 分词
    tokens = word_tokenize(text)
    
    # 获取特征集
    features = {word: True for word in tokens}
    
    # 加载情感分析数据集
    positive_reviews = [(movie_reviews.words(fileid), 'positive') for fileid in movie_reviews.fileids('pos')]
    negative_reviews = [(movie_reviews.words(fileid), 'negative') for fileid in movie_reviews.fileids('neg')]
    dataset = positive_reviews + negative_reviews
    
    # 构建训练数据集和测试数据集
    training_data = dataset[:800]
    testing_data = dataset[800:]
    
    # 训练模型
    classifier = NaiveBayesClassifier.train(training_data)
    
    # 测试模型准确率
    accuracy_score = accuracy(classifier, testing_data)
    
    # 分类结果
    sentiment = classifier.classify(features)
    
    # 返回分类结果
    return sentiment, accuracy_score