网站有关于我们的好处,网站开发工具总结,百度网站 收录,资源下载类网站源码实现LDA算法需要用到一些数学和概率统计的知识#xff0c;你需要根据LDA算法的具体公式#xff0c;实现初始化模型参数、Gibbs采样、模型参数更新等具体的步骤。同时#xff0c;还需要读取训练文件和词典文件#xff0c;以及保存模型到文件的功能。
理解LDA算法的实现思路…实现LDA算法需要用到一些数学和概率统计的知识你需要根据LDA算法的具体公式实现初始化模型参数、Gibbs采样、模型参数更新等具体的步骤。同时还需要读取训练文件和词典文件以及保存模型到文件的功能。
理解LDA算法的实现思路涉及到以下关键步骤
初始化模型参数 设置主题数K, 超参数alpha, beta。 初始化文档-主题分布 (theta) 和 主题-词汇分布 (phi)。
读取文档数据每行为一个文档分词后用空格隔开。 构建词典将每个词映射到唯一的整数。
class LDA:def __init__(self, alpha, beta, K, iter_num, top_words, wordmapfile, trnfile, modelfile_suffix):# ...def read_and_build_dictionary(self):# Read training file and build vocabulary# Implement code to read and build dictionary...初始化文档-主题分布和主题-词汇分布 为每个文档中的每个词随机分配一个主题。 根据分配的主题初始化文档-主题分布和主题-词汇分布。
class LDA:def __init__(self, alpha, beta, K, iter_num, top_words, wordmapfile, trnfile, modelfile_suffix):# ...def initialize(self):# ...# Initialize document-topic and topic-word distributionsself.theta np.random.dirichlet([self.alpha] * self.K, sizelen(self.documents))self.phi np.random.dirichlet([self.beta] * len(self.vocabulary), sizeself.K)Gibbs采样 对每个文档中的每个词进行Gibbs采样。 在采样过程中考虑当前文档-主题分布、主题-词汇分布以及词汇的分配情况。
class LDA:def __init__(self, alpha, beta, K, iter_num, top_words, wordmapfile, trnfile, modelfile_suffix):# ...def gibbs_sampling(self):# Implement Gibbs sampling algorithm...
更新模型参数 根据采样得到的文档-主题分布和主题-词汇分布更新模型的参数。 使用迭代方法逐步调整参数。
class LDA:def __init__(self, alpha, beta, K, iter_num, top_words, wordmapfile, trnfile, modelfile_suffix):# ...def update_model_parameters(self):# Update model parameters based on Gibbs sampling results# Implement parameter update code...
输出每个主题的前top_words个词 根据学习到的主题-词汇分布输出每个主题的前top_words个词以便观察主题的含义。
class LDA:def __init__(self, alpha, beta, K, iter_num, top_words, wordmapfile, trnfile, modelfile_suffix):# ...def print_top_words_per_topic(self):# Output top_words words for each topic based on learned phi# Implement code to print top words...
保存模型 将学习到的模型参数保存到文件以备后续使用。 class LDA:def __init__(self, alpha, beta, K, iter_num, top_words, wordmapfile, trnfile, modelfile_suffix):# ...def save_model(self):# Save model parameters, theta, phi, etc. to files# Implement code to save model...
实际实现中需要考虑数学计算的优化、数据结构的选择、算法的效率等方面的问题。详细的公式和算法细节可以参考LDA的相关文献。在实现过程中需要使用numpy等工具进行矩阵运算以提高效率。
实例 alpha 0.1 beta 0.1 K 10 //主题个数 iter_num 50 //迭代次数 top_words 20 //每个主题显示的词的个数 wordmapfile ‘./model/wordmap.txt’ //wordmap文件存储位置 trnfile “./model/test.dat” //训练文件 modelfile_suffix “./model/final” //模型文件的存储位置以及前缀 ‘’’ 输入文件的要求 每行为一篇文档分词后用空格隔开。 运行命令 ‘’’ python lda.py ‘’’ #!/usr/bin/env python
# -*- coding:utf-8 -*-import random,osalpha 0.1
beta 0.1
K 10
iter_num 50
top_words 20wordmapfile ./model/wordmap.txt
trnfile ./model/test.dat
modelfile_suffix ./model/finalclass Document(object):def __init__(self):self.words []self.length 0class Dataset(object):def __init__(self):self.M 0self.V 0self.docs []self.word2id {} # string,int字典self.id2word {} # int, string字典def writewordmap(self):with open(wordmapfile, w) as f:for k,v in self.word2id.items():f.write(k \t str(v) \n)class Model(object):def __init__(self, dset):self.dset dsetself.K Kself.alpha alphaself.beta betaself.iter_num iter_numself.top_words top_wordsself.wordmapfile wordmapfileself.trnfile trnfileself.modelfile_suffix modelfile_suffixself.p [] # double类型存储采样的临时变量self.Z [] # M*doc.size()文档中词的主题分布self.nw [] # V*K词i在主题j上的分布self.nwsum [] # K属于主题i的总词数self.nd [] # M*K文章i属于主题j的词个数self.ndsum [] # M文章i的词个数self.theta [] # 文档-主题分布self.phi [] # 主题-词分布def init_est(self):self.p [0.0 for x in xrange(self.K)]self.nw [ [0 for y in xrange(self.K)] for x in xrange(self.dset.V) ]self.nwsum [ 0 for x in xrange(self.K)]self.nd [ [ 0 for y in xrange(self.K)] for x in xrange(self.dset.M)]self.ndsum [ 0 for x in xrange(self.dset.M)]self.Z [ [] for x in xrange(self.dset.M)]for x in xrange(self.dset.M):self.Z[x] [0 for y in xrange(self.dset.docs[x].length)]self.ndsum[x] self.dset.docs[x].lengthfor y in xrange(self.dset.docs[x].length):topic random.randint(0, self.K-1)self.Z[x][y] topicself.nw[self.dset.docs[x].words[y]][topic] 1self.nd[x][topic] 1self.nwsum[topic] 1self.theta [ [0.0 for y in xrange(self.K)] for x in xrange(self.dset.M) ]self.phi [ [ 0.0 for y in xrange(self.dset.V) ] for x in xrange(self.K)]def estimate(self):print Sampling %d iterations! % self.iter_numfor x in xrange(self.iter_num):print Iteration %d ... % (x1)for i in xrange(len(self.dset.docs)):for j in xrange(self.dset.docs[i].length):topic self.sampling(i, j)self.Z[i][j] topicprint End sampling.print Compute theta...self.compute_theta()print Compute phi...self.compute_phi()print Saving model...self.save_model()def sampling(self, i, j):topic self.Z[i][j]wid self.dset.docs[i].words[j]self.nw[wid][topic] - 1self.nd[i][topic] - 1self.nwsum[topic] - 1self.ndsum[i] - 1Vbeta self.dset.V * self.betaKalpha self.K * self.alphafor k in xrange(self.K):self.p[k] (self.nw[wid][k] self.beta)/(self.nwsum[k] Vbeta) * \(self.nd[i][k] alpha)/(self.ndsum[i] Kalpha)for k in range(1, self.K):self.p[k] self.p[k-1]u random.uniform(0, self.p[self.K-1])for topic in xrange(self.K):if self.p[topic]u:breakself.nw[wid][topic] 1self.nwsum[topic] 1self.nd[i][topic] 1self.ndsum[i] 1return topicdef compute_theta(self):for x in xrange(self.dset.M):for y in xrange(self.K):self.theta[x][y] (self.nd[x][y] self.alpha) \/(self.ndsum[x] self.K * self.alpha)def compute_phi(self):for x in xrange(self.K):for y in xrange(self.dset.V):self.phi[x][y] (self.nw[y][x] self.beta)\/(self.nwsum[x] self.dset.V * self.beta)def save_model(self):with open(self.modelfile_suffix.theta, w) as ftheta:for x in xrange(self.dset.M):for y in xrange(self.K):ftheta.write(str(self.theta[x][y]) )ftheta.write(\n)with open(self.modelfile_suffix.phi, w) as fphi:for x in xrange(self.K):for y in xrange(self.dset.V):fphi.write(str(self.phi[x][y]) )fphi.write(\n)with open(self.modelfile_suffix.twords,w) as ftwords:if self.top_words self.dset.V:self.top_words self.dset.Vfor x in xrange(self.K):ftwords.write(Topic str(x)th:\n)topic_words []for y in xrange(self.dset.V):topic_words.append((y, self.phi[x][y]))#quick-sorttopic_words.sort(keylambda x:x[1], reverseTrue)for y in xrange(self.top_words):word self.dset.id2word[topic_words[y][0]]ftwords.write(\tword\tstr(topic_words[y][1])\n)with open(self.modelfile_suffix.tassign,w) as ftassign:for x in xrange(self.dset.M):for y in xrange(self.dset.docs[x].length):ftassign.write(str(self.dset.docs[x].words[y]):str(self.Z[x][y]) )ftassign.write(\n)with open(self.modelfile_suffix.others,w) as fothers:fothers.write(alpha str(self.alpha)\n)fothers.write(beta str(self.beta)\n)fothers.write(ntopics str(self.K)\n)fothers.write(ndocs str(self.dset.M)\n)fothers.write(nwords str(self.dset.V)\n)fothers.write(liter str(self.iter_num)\n)def readtrnfile():print Reading train data...with open(trnfile, r) as f:docs f.readlines()dset Dataset()items_idx 0for line in docs:if line ! :tmp line.strip().split()#生成一个文档对象doc Document()for item in tmp:if dset.word2id.has_key(item):doc.words.append(dset.word2id[item])else:dset.word2id[item] items_idxdset.id2word[items_idx] itemdoc.words.append(items_idx)items_idx 1doc.length len(tmp)dset.docs.append(doc)else:passdset.M len(dset.docs)dset.V len(dset.word2id)print There are %d documents % dset.Mprint There are %d items % dset.Vprint Saving wordmap file...dset.writewordmap()return dsetdef lda():dset readtrnfile()model Model(dset)model.init_est()model.estimate()if __name____main__:lda()
