从sparql查询结果中过滤掉某些属性 [英] filter out certain properties from sparql query result

问题描述

我正在尝试从sparql查询的结果中滤除某些属性（例如 dbpprop：的属性）。我正在查询dbpedia sparql endint。

I'm trying to filter out certain properties (e.g dbpprop: ones) from the result of a sparql query. I'm querying dbpedia sparql endoint.

更准确地说，我想做的事由以下伪代码表示：

More precisely what I'd like to do is expressed by the following pseudo code :

quantity_of_interest, property, value, property_type = sparqlQuery(query)
if property_type == rdf:Property:
    pass
else:
    return quantity_of_interest, property, value

现在，我随后用一些python过滤掉属性代码，然后使用以下sparql查询：

For now, I filter out the properties afterwards in some python code and I use the following sparql query :

SELECT DISTINCT ?qoi ?property ?value (bif:either(?type=rdf:Property, 0, 1) as ?filter_out) 
WHERE { 
    ?qoi a foaf:Person. ?qoi ?property ?value. 
    OPTIONAL{?property rdf:type ?type }
}

如果 filter_out == 0 我丢弃了整个结果。

If filter_out == 0 I discard the whole result.

有没有办法直接进行sparql查询，每当？type == rdf：Property ？

Is there a way I can directly make a sparql query which filters out the whole result whenever ?type == rdf:Property ?

推荐答案

您可以过滤出 dbprop：属性，

You can filter out dbprop: properties,

我正在尝试从$ b过滤掉某些属性（例如 dbpprop：的属性） $ b SPARQL查询的结果。我正在查询DBpedia SPARQL端点。

I'm trying to filter out certain properties (e.g., dbpprop: ones) from the result of a SPARQL query. I'm querying the DBpedia SPARQL endpoint.

如果要在结果集中绑定属性，并且要排除那些其结果集中的属性URI以 dbpprop：前缀开头，您可以使用

If you're binding properties in your result set, and you want to exclude ones whose URI begins with the dbpprop: prefix, you can do that with

filter(!strstarts(str(?p),str(dbpprop:)))

或者过滤出没有类型 rdf：Property 的属性。

您的伪代码看起来有点不同虽然：

or you can filter out properties that don't have type rdf:Property.

Your pseudocode looks like it's doing something slightly different though:

quantity_of_interest, property, value, property_type = sparqlQuery(query)
if property_type == rdf:Property:
    pass
else:
    return quantity_of_interest, property, value

每个属性都可以具有 rdf：Property 类型，因为它是RDF属性的类。 DBpedia可能没有拥有三重

Every property could have the type rdf:Property, since it's the class of RDF properties. DBpedia might not have the triple

p rdf:type rdf:Property

code>，当然，因此您仍然可以像这样过滤掉内容。如果那是您要执行的操作，则可以使用过滤器不存在{…} ：

for each property p, of course, so you may still be able to filter things out like this. If that's what you want to do, you can do it with filter not exists { … }:

filter not exists { ?p rdf:type rdf:Property }

DBpedia，现在就一样了。

事实证明，这些对DBpedia的影响相同，因为没有类型为 rdf：Property 和 ar 还具有 dbpprop：属性；以下查询返回 0 ：

For DBpedia, it's the same right now,

As it turns out, these will have the same effect on DBpedia, since there are no properties that have type rdf:Property and aren't also dbpprop: properties; the following query returns 0:

select (count(*) as ?num) where {
 ?p a rdf:Property
 filter( !strstarts( str(?p), str(dbpprop:) ) )
}
limit 100

，但一种选择是将来更兼容。

I d强烈建议您使用 strstarts 过滤器，而不要使用不存在。虽然属性的URI不能随时间改变（即URI是恒定的），但有关它的三元组可以更改。因此，如果您过滤掉 dbpprop：属性，那么您将永远不会意外过滤掉超出预期的内容。但是，如果您滤除类型为 rdf：Property 的内容，那么将来如果更多的 p rdf：type很容易丢失结果rdf：Property 添加了三元组（似乎这样的添加在逻辑上是兼容的）。

but one option is more future compatible.

I'd strongly suggest using the strstarts filter rather than the not exist here, though. While the URI of a property can't change over time (i.e., a URI is constant), the triples about it can change. Thus, if you filter out dbpprop: properties, then you'll never accidentally filter out more than you're expecting. However, if you filter out things that have rdf:Property as a type, then you can easily lose results in the future if more p rdf:type rdf:Property triples are added (and it seems like such an addition would be logically compatible).

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