Python RDF知识库查询

本文知识库查询使用SPARQL；
SPARQL (SPARQL Protocol and RDF Query Language)，是为RDF开发的一种查询语言和数据获取协议，它是为W3C所开发的RDF数据模型所定义，但是可以用于任何可以用RDF来表示的信息资源。
其语法格式如下:
SELECT ?Predicate ?Object where {http://baike.com/resource/华南师大?Predicate ?Object}
但是其返回的是三元组的形式,并不适合直接阅读,需要通过预处理。这里将《Python 将json格式文件转存为RDF格式文件》保存的RDF文件进行测试，代码如下：

# -*- coding: utf-8 -*-import rdflibimport reg1 = rdflib.Graph()g1.parse("data.rdf", format="xml")while 1:    print "please input the three words that you want,Subject,Predicate,Object;ues ',' to split them,ues '' if you don't know:"    try:        Subject, Predicate, Object = input()        data = ['', '', '']        if Subject != '' and Predicate == '' and Object == '':  # only search Subject            q = "select ?Predicate ?Object where { <http://baike.com/resource/" + \                Subject + "> ?Predicate ?Object}"            data[0] = Subject  # .encode('gbk')            x1 = g1.query(q)            if len(list(x1)) > 20:                leng = 20            else:                leng = len(list(x1))            for i in range(leng):                s = str(list(x1)[i]).decode('unicode_escape')                txt = re.findall(r'resource/.*?\'', s)                data[1] = txt[0][9:-1]                data[2] = txt[1][9:-1]                print data[0], data[1], data[2]        elif Subject == '' and Predicate != '' and Object == '':  # only search Predicate            q = "select ?Subject ?Object where {?Subject <http://baike.com/resource/" + \                Predicate + "> ?Object}"            data[1] = Predicate  # .encode('gbk')            x1 = g1.query(q)            if len(list(x1)) > 20:                leng = 20            else:                leng = len(list(x1))            for i in range(leng):                s = str(list(x1)[i]).decode('unicode_escape')                txt = re.findall(r'resource/.*?\'', s)                data[0] = txt[0][9:-1]                data[2] = txt[1][9:-1]                print data[0], data[1], data[2]        elif Subject == '' and Predicate == '' and Object != '':  # only search Object            q = "select ?Subject ?Predicate where {?Subject ?Predicate <http://baike.com/resource/" + Object + ">}"            data[2] = Object  # .encode('gbk')            x1 = g1.query(q)            if len(list(x1)) > 20:                leng = 20            else:                leng = len(list(x1))            for i in range(leng):                s = str(list(x1)[i]).decode('unicode_escape')                txt = re.findall(r'resource/.*?\'', s)                data[0] = txt[0][9:-1]                data[1] = txt[1][9:-1]                print data[0], data[1], data[2]        elif Subject != '' and Predicate != '' and Object == '':  # search Subject and Predicate            q = "select ?Object where {<http://baike.com/resource/" + Subject + ">\        <http://baike.com/resource/" + Predicate + "> ?Object}"            data[0] = Subject  # .encode('gbk')            data[1] = Predicate  # .encode('gbk')            x1 = g1.query(q)            if len(list(x1)) > 20:                leng = 20            else:                leng = len(list(x1))            for i in range(leng):                s = str(list(x1)[i]).decode('unicode_escape')                txt = re.findall(r'resource/.*?\'', s)                data[2] = txt[0][9:-1]                print data[0], data[1], data[2]        elif Subject != '' and Predicate == '' and Object != '':  # search Subject and Object            q = "select ?Predicate where {<http://baike.com/resource/" + Subject + ">  ?Predicate \        <http://baike.com/resource/" + Object + ">}"            data[0] = Subject  # .encode('gbk')            data[2] = Object  # .encode('gbk')            x1 = g1.query(q)            if len(list(x1)) > 20:                leng = 20            else:                leng = len(list(x1))            for i in range(leng):                s = str(list(x1)[i]).decode('unicode_escape')                txt = re.findall(r'resource/.*?\'', s)                data[1] = txt[0][9:-1]                print data[0], data[1], data[2]        elif Subject == '' and Predicate != '' and Object != '':  # search Predicate and Object            q = "select ?Subject where { ?Subject <http://baike.com/resource/" + Predicate + ">\        <http://baike.com/resource/" + Object + ">}"            data[1] = Predicate  # .encode('gbk')            data[2] = Object  # .encode('gbk')            x1 = g1.query(q)            if len(list(x1)) > 20:                leng = 20            else:                leng = len(list(x1))            for i in range(leng):                s = str(list(x1)[i]).decode('unicode_escape')                txt = re.findall(r'resource/.*?\'', s)                data[0] = txt[0][9:-1]                print data[0], data[1], data[2]        elif Subject != '' and Predicate != '' and Object != '':  # search all            q = "select ?Predicate ?Object where { <http://baike.com/resource/" + \                Subject + "> ?Predicate ?Object}"            data[0] = Subject  # .encode('gbk')            x1 = g1.query(q)            if len(list(x1)) > 20:                leng = 20            else:                leng = len(list(x1))            for i in range(leng):                s = str(list(x1)[i]).decode('unicode_escape')                txt = re.findall(r'resource/.*?\'', s)                data[1] = txt[0][9:-1]                data[2] = txt[1][9:-1]                print data[0], data[1], data[2]        else:            break    except:        pass

考虑到当数据量很大时，把所有匹配的结果显示出来太花时间，就只显示查询到的前20条
测试结果：

输入是三元组的任意一个或者任意两个或者全部，以逗号分割，当输入格式错误时pass

测试数据及程序：点击下载