本文内容源自medium文章
A Knowledge Graph understanding and implementation tutorial for beginners[1]
什么是知识图谱？
知识图谱的内容通常以三元组形式存在，Subject-Predicate-Object (spo)。
举个栗子：
Leonard Nimoy was an actor who played the character Spock in the science-fiction movie Star Trek
对上面的句子可以抽取到如下三元组：
以知识图谱形式可以表示为：
上述由节点和关系组成的图，就是一个简单的知识图谱。
如何搭建一个简单的知识图谱？
可以分为以下两大步骤：
- 知识提取
- 信息抽取，获取三元组
- 实体识别、实体链接、实体消歧(Disambiguation)、实体统一(Entity Resolution)
- 图构建
- 存储
- 查询
知识提取步骤是构建知识图谱的关键，三元组可以通过依存分析得到。
动手构建一个简单知识图谱
此处只显示代码执行过程与结果，完整代码请见github.
1. 三元组提取
借助spacy
inputText = 'Startup companies create jobs and innovation. Bill Gates supports entrepreneurship.'
# Step 1: Knowledge Extraction. Output: SOP triples
knowledgeExtractionObj = KnowledgeExtraction()
sop_list = knowledgeExtractionObj.retrieveKnowledge(inputText)
#list_sop = sop_list.as_doc()
sop_list_strings = []
for sop in sop_list:
temp = []
temp.append(sop[0].text)
temp.append(sop[1].text)
temp.append(sop[2].text)
sop_list_strings.append(temp)
print(sop_list_strings)
结果
2. 实体链接
# Step 2: Entity recognition and linking. This step needs to be linked.
entityRecognitionLinkingObj = EntityRecognitionLinking()
entityRelJson = entityRecognitionLinkingObj.entityRecogLink(inputText)
entityLinkTriples = []
for sop in sop_list_strings:
tempTriple = ['', '', '']
for resource in entityRelJson['Resources']:
if resource['@surfaceForm'] == sop[0]:
tempTriple[0] = resource['@URI']
if resource['@surfaceForm'] == sop[1]:
tempTriple[1] = resource['@URI']
if resource['@surfaceForm'] == sop[2]:
tempTriple[2] = resource['@URI']
entityLinkTriples.append(tempTriple)
print(entityLinkTriples)
结果
3. 图构建
使用neo4j
# Step 3: Knowledge Graph creation.
graphPopulationObj = GraphPopulation()
graphPopulationObj = graphPopulationObj.popGraph(
sop_list_strings, entityLinkTriples)
最终得到图如下：
可能遇到的问题
- Q1
AuthError: The client is unauthorized due to authentication failure.
解决办法：
确保图数据库配置时密码一致与设置的一致 (以下配置表示，user：neo4j，password：neo4j)
config.DATABASE_URL = 'bolt://neo4j:neo4j@localhost:7687'#default
- Q2
ServiceUnavailable: Failed to establish connection to ('127.0.0.1', 7687) (reason [WinError 10061] 由于目标计算机积极拒绝，无法连接。)
解决办法：
确保在执行图创建代码前已经打开neo4j
有问题欢迎留言，一起交流
[2]https://github.com/kramankishore/Knowledge-Graph-Intro
[3]https://neomodel.readthedocs.io/en/latest/getting_started.html#connecting
[4]https://www.analyticsvidhya.com/blog/2019/10/how-to-build-knowledge-graph-text-using-spacy/