7

我承认这基本上是在本地服务器上使用 freebase 数据的重复问题?但我需要比那里已经给出的更详细的答案

我已经完全爱上了 Freebase。我现在想要的是创建一个非常简单的 Freebase 克隆,用于存储可能不属于 Freebase 本身但可以使用 Freebase 模式描述的内容。本质上,我想要的是一种简单而优雅的方式来存储像 Freebase 本身那样的数据,并且能够在 Python (CherryPy) Web 应用程序中轻松使用该数据。

MQL 参考指南的第 2 章指出:

Metaweb 基础的数据库与您可能熟悉的关系数据库根本不同。关系数据库以表格的形式存储数据,但Metaweb 数据库将数据存储为节点图和这些节点之间的关系

我猜这意味着我应该使用三重存储或图形数据库,例如 Neo4j?这里有没有人有使用 Python 环境中的其中一个的经验?

(到目前为止,我实际上尝试的是创建一个能够轻松存储 Freebase 主题的关系数据库模式,但我在配置 SQLAlchemy 中的映射时遇到了问题)。

我正在调查的事情

更新 [28/12/2011]:

我在 Freebase 博客上发现了一篇文章,描述了 Freebase 自己使用的专有元组存储/数据库(图表):http ://blog.freebase.com/2008/04/09/a-brief-tour-of-graphd/

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6 回答 6

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于 2012-09-14T16:10:09.140 回答
6

我的2美分...

我使用一点 Java 代码将 Freebase 数据转储转换为 RDF:https ://github.com/castagna/freebase2rdf

我使用 Apache Jena 的 TDB 存储加载 RDF 数据,并使用 Fuseki 通过 HTTP 上的 SPARQL 协议提供数据。

也可以看看:

于 2012-03-11T18:38:28.170 回答
3

SPARQL 是查询 RDF 的查询语言,它允许编写类似 SQL 的查询。大多数 RDF 数据库都实现了 SPARQL 接口。此外,Freebase 允许您在 RDF 中导出数据,因此您可以直接在 RDF 数据库中使用该数据并使用 SPARQL 查询它。

我会看一下本教程以更好地了解 SPARQL。

如果你要处理一个大数据集,比如 freebase,我会使用4store和任何Python 客户端。4store 通过 HTTP 公开 SPARQL,您可以发出 HTTP 请求来断言、删除和查询数据。它还处理 JSON 格式的结果集,这对于 Python 来说非常方便。我在几个项目中使用了这个基础设施,不是用 CherryPy,而是用 Django,但我想这种差异并不重要。

于 2011-12-27T00:42:00.613 回答
3

对于 freebase 转储用户来说,一个好消息是 Freebase 现在提供 RDF 转储:http ://wiki.freebase.com/wiki/Data_dumps 。它是海龟格式,因此使用为 RDF 设计的任何图形数据库都非常方便。

我的建议也是 4store: http://4store.org/。它简单易用。您可以使用 http 请求来执行 SPARQL 操作。

我的项目中一件棘手的事情是“。” Freebase 转储中使用的(表示缩短 URL)无法被 4store 识别。所以我在所有包含“。”的列中添加一个括号“<>”。并自己处理缩短的 URL。

于 2013-02-19T19:47:41.357 回答
1

看看https://cayley.io。我相信它是由同一作者编写的,并且使用与graphdFreebase 的后端相同的原理,在 Google 杀死它之前。

关于数据,您可能需要运行类似这样的操作来清理Freebase DB 转储或使用datahub

于 2017-03-24T17:10:39.710 回答
0

这是我其他答案的额外代码。肉在 edb.py 中。从 Python 控制台运行并按照示例进行操作。或者使用 web2py 控制器并在浏览器中运行。

将此保存为 edb.py:

import MySQLdb
import sys

connection = MySQLdb.connect (host   = "localhost",
                              user   = "root",
                              passwd = "x",
                              db     = "y")
cursor = connection.cursor()

query_counter = 0
print_queries = False
limit         = 1000

def fetch_one( query ):
    global query_counter, print_queries
    query = query + ' LIMIT ' + str(limit)
    if print_queries:
        print query
    cursor = connection.cursor()
    cursor.execute( query )
    query_counter += 1
    result = cursor.fetchone() 
    if result:
        return result[0]
    else:
        return None

def fetch_all( query ):
    global query_counter, print_queries
    query = query + ' LIMIT ' + str(limit)
    if print_queries:
        print query
    cursor = connection.cursor()
    cursor.execute( query )
    query_counter += 1
    return cursor.fetchall()

def _flatten( list_of_lists ):
    import itertools
    return list(itertools.chain(*list_of_lists))

#Example: e._search_by_name('steve martin')
def _search_by_name( name, operator = '=' ):
    typed, ranked = {}, []
    if name:
        name = name.strip()
    if not name:
        return ( typed, ranked )

    filler = '' if operator == '=' else '%'
    ranks = {}

    #to filter meaningful stuff for every mid returned order by the number of types they have

    #search for value text if prop. is 
    #select * from ns where value = 'the king' and (property = '/m/01gr' or property = '/m/06b');

    name_mid  = _mid( '/type/object/name'   )
    alias_mid = _mid( '/common/topic/alias' )

    query = "select ns.source from ns where ns.value %s '%s%s' and ns.property in ('%s', '%s')" % ( operator, name, filler, name_mid, alias_mid )

    for i in fetch_all( query ):
        typed[ i[0] ] = _types( i[0] )

    import operator
    ranked = [ ( len( typed[i] ), i ) for i in typed ]
    ranked = [ e[1] for e in sorted( ranked, key=operator.itemgetter(0), reverse = True ) ]

    return (typed, ranked)


#Example: e._children('')               <---will get the top level domains
#         e._children('/film')          <---get all types from the domain
#         e._children('/film/film')     <---get all properties for the type
def _children( parent, expand = False, raw = False ):
    query = "select t.source, t.value from types t where t.destination = '%s'" % (parent)
    res = fetch_all( query )
    if raw:
        return [ row[0] for row in res ]
    if expand: prefix = parent
    else:      prefix = ''
    return [ prefix + '/' + row[1] for row in fetch_all(query) ]

#Example: e._parent('/film/film/songs')
def _parent( child ):                                       # '/people/marriage/to' -> '/people/marriage'
    #if not isinstance( child, str ): return None          # what kind of safety mechanisms do we need here?
    return '/'.join(child.split('/')[:-1])

#Example: e._domains()
def _domains():
    return _children('')

#Example: e._top_level_types()
def _top_level_types():
    return _children('/type')

#TODO get all primitive types

#Example: e._mid('/type/object')
#         e._mid('/authority/imdb/name/nm0000188')
def _mid( key ):
    if key == '':
        return None
    elif key == '/':
        key = '/boot/root_namespace'
    parts = key.split('/')
    if parts[1] == 'm':            #already a mid
        return key
    namespace = '/'.join(parts[:-1])
    key = parts[-1]
    return fetch_one( "select source from types t where t.destination = '%s' and t.value = '%s'" % (namespace, key) )

#Example: e._key('/type')
def _key( mid ):
    if isinstance( mid, str):
        res = _keys( mid )
        if not res:
            return None
        rt  = [ r for r in res if r.startswith( '/type' ) ]
        if rt:
            return rt[0]
        else:
            return res[0]
    elif isinstance( mid, list ) or isinstance( mid, tuple ):
        res = [ _key( e ) for e in mid ]
        return [ r for r in res if r is not None ]
    else:
        return None

def _keys( mid ):
    # check for '/type/object/key' as well?
    query = "select t.destination, t.value from types t where t.source = '%s'" % mid
    return [ row[0]+'/'+row[1] for row in fetch_all( query ) ]

#Example: e._types('/m/0p_47')
def _types( mid ):
    tm = _mid( '/type/object/type' )
    query = "select l.destination from links l where l.source = '%s' and l.property = '%s'" % (mid, tm)
    return [ row[0] for row in fetch_all( query ) ]

#Example: e._props_n('/m/0p_47')   <---Named immediate properties (like name, etc.)
def _props_n( mid ):  #the same property can be set more than once per topic!
    query = "select ns.property from ns where ns.source = '%s'" % (mid)
    return list( set( [ row[0] for row in fetch_all( query ) ] ) )

#Example: e._props_l('/m/0p_47')   <---All remote properties, some are named, some are anonymous
def _props_l( mid ):  #the same property can be set more than once per topic!
    tm = _mid( '/type/object/type' )    #exclude types, they have tons of instance links
    res = fetch_all( "select l.property, l.destination from links l where l.source = '%s' and property <> '%s'" % (mid, tm) )
    output = {}
    for r in res:
        dests = output.get( r[0], False )
        if dests:
            dests.append( r[1] )
        else:
            output[ r[0] ] = [ r[1] ]
    return output

#Example: e._props_ln('/m/0p_47')  <---All remote named properties
def _props_ln( mid ): #named properties
    result = []
    ps = _props_l( mid )
    common_topic = _mid( '/common/topic' )
    for p in ps:
        ts = _types( ps[p][0] )
        if common_topic in ts:               #it's a common topic
            result.append( p )
    return result

#Example: e._props_la('/m/0p_47')  <---All remote anonymous properties, these actually belong to the children!
#instead of has type /common/topic we used to check if it has name
def _props_la( mid, raw = True ): #anonymous properties (blank nodes in RDF?)
    result = []
    ps = _props_l( mid )
    common_topic = _mid( '/common/topic' )
    for p in ps:
        ts = _types( ps[p][0] )
        if common_topic not in ts:                                       #it is not a common topic
            t = _key( _types( ps[p][0] ) )
            if t and '/type/type' not in t:                              #FIXME: hack not to go into types, could be done better
                result.append( _children( t[0], expand=True, raw=raw ) ) #get the first, is this correct?
    return _flatten( result )                                            #it is a list of lists

#FIXME: try to get '/film/actor/film' -> '/type/property/expected_type' -> '/film/performance' -> properties/children 
#instead of trying is something has name

#Example: e._get_n('/m/0p_47', e._props_n('/m/0p_47')[0])['/lang/en'] <---These come with a namespace
def _get_n( mid, prop ):  #the same property can be set more than once per topic!
    p = _mid( prop )
    query = "select ns.value from ns where ns.source = '%s' and ns.property = '%s'" % (mid, p)
    return [ r[0] for r in fetch_all( query ) ]

#Example: e._get_l('/m/0p_47', e._props_l('/m/0p_47')[0])  <---returns a list of mids coresponding to that prop.
#         e._name(e._get_l('/m/0p_47', '/film/writer/film'))          
def _get_l( mid, prop ):  #the same property can be set more than once per topic!
    p = _mid( prop )
    query = "select l.destination from links l where l.source = '%s' and l.property = '%s'" % (mid, p)
    return  [ row[0] for row in fetch_all( query ) ]           

#Example: e._name(e._get_ln('/m/0p_47', e._props_ln('/m/0p_47')[0]))
def _get_ln( mid, p ):        #just alias for _get_l, keeping for consistency
    return _get_l( mid, p )                                 

#Example: e._name(e._get_la('/m/0p_47', '/film/performance/film'))
def _get_la( mid, prop ):
    result = []
    ps = _props_l( mid )
    for p in ps:
        es = _get_l( mid, p )                       #get the destinations
        if not es: continue
        ts = set( _types( es[0] ) )
        if _mid(_parent(_key(_mid(prop)))) in ts:   #should be able to do this more efficiently!!!
            for e in es:
                result.append( _get_l( e, prop ) )
            return _flatten( result )               #return after the first result 

#How do we determine properties with multiple values vs those with singular (i.e. place of birth)?
#is this in the ontology?
#Ans: yes, /type/property/unique

#Example: e._all_names_ln('/m/0p_47')  <---gets all of object's remote named properties
def _all_names_ln( mid ):
    result = {}
    for p in _props_ln( mid ):
        result[ _key(p) ] = _name( _get_ln( mid, p ) )
    return result 

#Example: e._all_names_la('/m/0p_47')  <---gets all of object's remote anonymous properties
def _all_names_la( mid ):       #TODO: prevent loops, run e.all_names_la('/m/0p_47')
    result = {}
    for p in _props_la( mid ):
        result[ _key( p ) ] = _name ( _get_la( mid, p ) )
    return result 

#FIXME: _all_names_la is going into destinations which are types and have a ton of instance links...


#Example: e._name('/m/0p_47')   <---the name of a topic
#
def _name( mid ):
    if isinstance( mid, str ):
        nm = _mid( '/type/object/name' )
        return _get_n( mid, nm )
    elif isinstance( mid, list ) or isinstance( mid, tuple ) or isinstance( mid, set ):
        return [ _name( e ) for e in mid ]
    else:
        return None

#for internal use only
def _get_linked( mid ):
    tm = _mid( '/type/object/type' )    #exclude types, they have tons of instance links
    query = "select destination from links where source = '%s' and property <> '%s' " % ( mid, tm )
    return set( [ r[0] for r in fetch_all( query ) ] )

#for internal use only
def _get_connections_internal( entity1, target, path, all_paths, depth, max_depth):
    import copy

    if depth > max_depth:
        return

    if True:
        print
        print str(entity1) + ', ' + str(target)
        print str( path )
        print str( all_paths )
        print depth

    path.append( entity1 )

    linked1 = _get_linked( entity1 )

    if target in linked1 or entity1 == target:
        path.append( target )
        all_paths.append( path )
        #print str( path )
        return

    for l1 in linked1:
        if l1 in path:
            continue
        _get_connections_internal( l1, 
                                   target, 
                                   copy.copy( path ),
                                   all_paths,
                                   depth+1, 
                                   max_depth )

#Example: e._name(e._get_connections('/m/0p_47', '/m/0cwtm'))  <---find path in the graph between the two entities    
def _get_connections( entity1, target ):
    result = []
    _get_connections_internal( entity1, target, [], result, 0, 2 )
    return result

#for internal use only
def _get_connections_internal2( entity1, entity2, path1, path2, all_paths, depth, max_depth, level ):
    import copy

    if depth > max_depth:
        return

    if level < 0: level = 0

    path1.append( entity1 )
    path2.append( entity2 )

    if entity1 == entity2 and level == 0:
        all_paths.append( ( path1, path2 ) ) #no need to append entity1 or entity2 to the paths
        return

    linked1 = _get_linked( entity1 )
    if entity2 in linked1 and entity2 not in path1 and level == 0:
        path1.append( entity2 )
        all_paths.append( ( path1, path2 ) )
        return

    linked2 = _get_linked( entity2 )
    if entity1 in linked2 and entity1 not in path2 and level == 0:
        path2.append( entity1 )
        all_paths.append( ( path1, path2 ) )
        return

    inters = linked1.intersection( linked2 )
    inters = inters.difference( set( path1 ) )
    inters = inters.difference( set( path2 ) )

    if inters and level == 0:
        for e in inters:               #these are many paths, have to clone
            p1 = copy.copy( path1 )
            p1.append( e )
            p2 = copy.copy( path2 )
            p2.append( e )
            all_paths.append( ( p1,p2 ) )
        return

    for l1 in linked1:
        if l1 in path1 or l1 in path2:
            continue
        for l2 in linked2:
            if l2 in path1 or l2 in path2:
                continue
            _get_connections_internal2( l1,                 l2, 
                                        copy.copy( path1 ), copy.copy( path2 ),
                                        all_paths,
                                        depth+1, 
                                        max_depth,
                                        level - 1 )

#Example: e._name(e._get_connections2('/m/0p_47', '/m/0cwtm'))          <---returns two meeting paths starting from both entities
#         e._name(e._get_connections('/m/0p_47', '/m/0cwtm', level=1))  <---search deeper
#         e._name(e._get_connections('/m/0p_47', '/m/0cwtm', level=2))  <---even deeper
def _get_connections2( entity1, entity2, level = 0 ):
    result = []
    _get_connections_internal2( entity1, entity2, [], [], result, 0, 15, level )
    return result

这是一个示例 web2py 控制器(只需将 edb.py 复制到 web2py 模型目录中):

# -*- coding: utf-8 -*-

def mid_to_url( mid ):
    return mid.split('/')[2]

def index():

    form = FORM( TABLE( TR( INPUT(_name='term', _value=request.vars.term ) ),
                        TR(INPUT(_type='submit', _value='Search') ) ),
                 _method='get')

    typed, ranked = _search_by_name( request.vars.term )

    rows = []

    for r in ranked:
        keys = []
        for t in typed[r]:
            k = _key( t )
            if k:
                keys.append( k )
        rows.append( TR( TD( A(_name( r ), 
                               _href = URL('result', args = [mid_to_url(r)]))), 
                         TD( XML( '<br/>'.join( keys ) ) ) ) )

    result = TABLE( *rows )

    return { 
             'form': form, 
             'result' : result 
             }

def result():
    path, data = '', ''
    if not request.args:
        return { 'path':path, 'data':data}

    path_rows = []
    for ra in range(len(request.args)):
        if ra%2:
            arrow_url = URL( 'static', 'images/blue_arr.png' )
            display_name = _key('/m/'+request.args[ra])        #it's a property
        else:
            arrow_url = URL( 'static', 'images/red_arr.png' )
            display_name = _name('/m/'+request.args[ra])       #it's a topic
        path_rows.append( TD( A( display_name, _href=URL( args = request.args[0:ra+1] ) ) ) )
        path_rows.append( TD( IMG( _src = arrow_url ) ) )
    path = TABLE( *path_rows )

    elems = [ '/m/'+a  for a in request.args ]
    if _mid( '/type/property' ) in _types( elems[-1] ): #we are rendering a property
        objects = _get_ln( elems[-2], elems[-1] )
        if not objects: #there should be a better way to see if this is anonymous
            objects = _get_la( elems[-2], elems[-1] )

        data = TABLE( *[ TR( TD( A(_name(o), _href = URL( args = request.args+[mid_to_url(o)])))) for o in objects ] )

    else:                                               #we are rendering a topic
        direct_props = TABLE(*[TR(TD(_key(p)), TD(', '.join(_get_n( elems[-1], p)))) for p in _props_n( elems[-1] )])
        linked_named_props = TABLE(*[TR(TD(A(_key(p), 
                                             _href = URL(args = request.args+[mid_to_url(p)])))) for p in _props_ln( elems[-1] ) ] )
        linked_anon_props = TABLE(*[TR(TD(A(_key(p), 
                                            _href = URL(args = request.args+[mid_to_url(p)])))) for p in _props_la( elems[-1] ) ] )

        data = TABLE( TR( TH( 'Linked named data:'), TH( 'Linked anonymous data:' ), TH( 'Direct data:' ) ), 
                      TR( TD( linked_named_props ), TD( linked_anon_props ), TD( direct_props ) ) )

    return { 'path': path, 'data':data }
于 2012-09-14T16:15:17.080 回答