python 全文检索引擎详解
最近一直在探索着如何用Python实现像百度那样的关键词检索功能。说起关键词检索，我们会不由自主地联想到正则表达式。正则表达式是所有检索的基础，python中有个re类，是专门用于正则匹配。然而，光光是正则表达式是不能很好实现检索功能的。
python有一个whoosh包，是专门用于全文搜索引擎。
whoosh在国内使用的比较少，而它的性能还没有sphinx/coreseek成熟，不过不同于前者，这是一个纯python库，对python的爱好者更为方便使用。具体的代码如下
安装
输入命令行 pip install whoosh
需要导入的包有:
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fromwhoosh.index import create_infromwhoosh.fields import *fromwhoosh.analysis import RegexAnalyzerfromwhoosh.analysis import Tokenizer,Token |
中文分词解析器
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class ChineseTokenizer(Tokenizer): """ 中文分词解析器 """ def __call__(self, value, positions=False, chars=False, keeporiginal=True, removestops=True, start_pos=0, start_char=0, mode='', **kwargs): assert isinstance(value, text_type), "%r is not unicode "% value t = Token(positions, chars, removestops=removestops, mode=mode, **kwargs) list_seg = jieba.cut_for_search(value) for w in list_seg: t.original = t.text = w t.boost = 0.5 if positions: t.pos = start_pos + value.find(w) if chars: t.startchar = start_char + value.find(w) t.endchar = start_char + value.find(w) + len(w) yield tdef chinese_analyzer(): return ChineseTokenizer() |
构建索引的函数
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@staticmethod def create_index(document_dir): analyzer = chinese_analyzer() schema = Schema(titel=TEXT(stored=True, analyzer=analyzer), path=ID(stored=True), content=TEXT(stored=True, analyzer=analyzer)) ix = create_in("./", schema) writer = ix.writer() for parents, dirnames, filenames in os.walk(document_dir): for filename in filenames: title = filename.replace(".txt", "").decode('utf8') print title content = open(document_dir + '/' + filename, 'r').read().decode('utf-8') path = u"/b" writer.add_document(titel=title, path=path, content=content) writer.commit() |
检索函数
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@staticmethod def search(search_str): title_list = [] print 'here' ix = open_dir("./") searcher = ix.searcher() print search_str,type(search_str) results = searcher.find("content", search_str) for hit in results: print hit['titel'] print hit.score print hit.highlights("content", top=10) title_list.append(hit['titel']) print 'tt',title_list return title_list |
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原文链接：http://blog.csdn.net/qq_30843221/article/details/48184311
