python 实现倒排索引的方法

#encoding:utf-8fin = open('1.txt', 'r')'''建立正向索引: “文档1”的ID > 单词1：出现位置列表；单词2：出现位置列表；………… “文档2”的ID > 此文档出现的关键词列表。'''forward_index = {}for line in fin: line = line.strip().split() forward_index[int(line[0])] = {} words = line[1].split(',') for i, index in enumerate(words):  if int(index) not in forward_index[int(line[0])].keys():   forward_index[int(line[0])][int(index)] = [i]  else:   forward_index[int(line[0])][int(index)].append(i)print 'forward_index:', forward_index'''建立倒排索引： “关键词1”：“文档1”的ID，“文档2”的ID，………… “关键词2”：带有此关键词的文档ID列表。'''inverted_index = {}for doc_id, words in forward_index.items(): for word_id in words.keys():  if word_id not in inverted_index.keys():   inverted_index[word_id] = [doc_id]  elif doc_id not in inverted_index[word_id]:   inverted_index[word_id].append(doc_id)print 'inverted_index:', inverted_index

1 3,4 2 3,4,2,4 3 2

forward_index: {1: {3: [0], 4: [1]}, 2: {2: [2], 3: [0], 4: [1, 3]}, 3: {2: [0]}} inverted_index: {2: [2, 3], 3: [1, 2], 4: [1, 2]}