SPARQL-未知的名称空间前缀错误 [英] SPARQL - Unknown namespace prefix error

问题描述

我有一个导入了rdflib的python文件，并实现了一些SPARQL查询

I have a python file with imported rdflib and some SPARQL query implemented

from rdflib import Graph
import html5lib

if __name__ == '__main__':
    g = Graph()

    g.parse('http://localhost:8085/weather-2.html', format='rdfa')

res1 = g.parse('http://localhost:8085/weather-2.html', format='rdfa')
print(res1.serialize(format='pretty-xml').decode("utf-8"))
print()

res2 = g.query("""SELECT ?obj
    WHERE { <http://localhost:8085/weather-2.html> weather:region ?obj . }
    """)
for row in res2:
    print(row)

res1可以轻松打印出来，但是对于res2，我收到一条错误消息:

res1 has no trouble to print out but for res2 I get an error saying:

Exception: Unknown namespace prefix : weather

显然，这是由于根据我所用的编辑器pycharm，第15行出现错误.

Apparently this is due to an error on line 15 according to pycharm, the editor I am using to implement this.

我遗漏了什么导致此错误? 在SPARQL查询中仅调用weather:region还有其他功能吗? 如果可以，该如何解决此问题?

What am I missing that is causing this error? Is there more to just calling weather:region in my SPARQL query? If so how to do fix this problem?

推荐答案

如错误消息所示，未定义名称空间weather:-因此在SPARQL中，您需要使用PREFIX来定义天气，例如:

As the error message suggests, the namespace weather: is not defined - so in the SPARQL you either need a PREFIX to define weather, like:

PREFIX weather: <weatheruri>

PREFIX weather: <weatheruri>

或者您应该放置明确的天气URI而不是weather:

Or you should put the explicit weather URI instead of the weather:

天气名称空间URI(或称为IRI?)将在rdf文档的XML名称空间中-它以/或#结尾，因此，如果URI为http://weather.com/，则前缀定义为PREFIX weather: <http://weather.com/>

The weather namespace URI (or is it called an IRI?) will be in the XML namespaces in the rdf document - it will end with / or # so if the URI is http://weather.com/ the prefix definition is PREFIX weather: <http://weather.com/>

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