Sparql 查询仅获取匹配条件的最顶层元素

Question

我有多个节点与 hasParent 链接的树，每个节点都有一些特定的颜色。我需要按颜色过滤一棵树并提取最顶层的元素（过滤后排除嵌套元素）。

这是我的数据示例：

我需要的结果是：[A, B, I].

我知道如何实现 returns [A, B, I, J, L, O]:

的基本树过滤器

SELECT DISTINCT ?s WHERE {
  ?s <http://looneytunes-graph.com/color> "yellow"^^xsd:string
}

有没有办法实现这种额外的过滤？还是我需要重新考虑我的解决方案并使用其他东西代替图形数据库 (AWS Neptune)？

我正在使用 https://sparql-playground.sib.swiss/data 和以下数据对其进行测试：

@prefix xsd: <http://www.w3.org/2001/XMLSchema#> .

<http://looneytunes-graph.com/A> <http://looneytunes-graph.com/color> "yellow"^^xsd:string .

<http://looneytunes-graph.com/B> <http://looneytunes-graph.com/color> "yellow"^^xsd:string .

<http://looneytunes-graph.com/C> <http://looneytunes-graph.com/color> "green"^^xsd:string .

<http://looneytunes-graph.com/D> <http://looneytunes-graph.com/color> "red"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/A> .

<http://looneytunes-graph.com/E> <http://looneytunes-graph.com/color> "blue"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/A> .

<http://looneytunes-graph.com/F> <http://looneytunes-graph.com/color> "blue"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/B> .

<http://looneytunes-graph.com/G> <http://looneytunes-graph.com/color> "green"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/B> .

<http://looneytunes-graph.com/H> <http://looneytunes-graph.com/color> "red"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/C> .

<http://looneytunes-graph.com/I> <http://looneytunes-graph.com/color> "yellow"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/C> .

<http://looneytunes-graph.com/J> <http://looneytunes-graph.com/color> "yellow"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/D> .

<http://looneytunes-graph.com/K> <http://looneytunes-graph.com/color> "green"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/D> .

<http://looneytunes-graph.com/L> <http://looneytunes-graph.com/color> "yellow"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/F> .

<http://looneytunes-graph.com/M> <http://looneytunes-graph.com/color> "red"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/G> .

<http://looneytunes-graph.com/N> <http://looneytunes-graph.com/color> "blue"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/G> .

<http://looneytunes-graph.com/O> <http://looneytunes-graph.com/color> "yellow"^^xsd:string ;
    <http://looneytunes-graph.com/hasParent> <http://looneytunes-graph.com/I> .

Answer 1

SELECT DISTINCT ?s WHERE {
  ?s <http://looneytunes-graph.com/color> "yellow"^^xsd:string .
  FILTER NOT EXISTS {
     ?s hasParent+ [<http://looneytunes-graph.com/color> "yellow"^^xsd:string] .
  }
}

通过此查询，您将过滤掉具有黄色父节点（一个父节点具有一个父节点具有...）的节点。

Sparql 查询仅获取匹配条件的最顶层元素

Sparql query to get only top-most elements matching criteria

rdf

sparql