在基本 sparql 查询中应用基于正则表达式的过滤器 returns 无结果

Question

以下查询：

PREFIX qb: <http://purl.org/linked-data/cube#>
SELECT DISTINCT ?subject
WHERE 
{
  ?x qb:component ?subject .
}

通过此公开端点部署：http://statistics.gov.scot/sparql-beta 生成可用主题列表：

http://statistics.gov.scot/def/component-specification/pupil-attainment/refArea
http://statistics.gov.scot/def/component-specification/pupil-attainment/refPeriod
http://statistics.gov.scot/def/component-specification/pupil-attainment/measureType
http://statistics.gov.scot/def/component-specification/pupil-attainment/count
http://statistics.gov.scot/def/component-specification/pupil-attainment/pupils
http://statistics.gov.scot/def/component-specification/pupil-attainment/ratio

问题

我想使用正则表达式过滤可用结果，类似于 linked example:

PREFIX vcard: <http://www.w3.org/2001/vcard-rdf/3.0#>

SELECT ?g
WHERE
{ ?y vcard:Given ?g .
  FILTER regex(?g, "r", "i") }

尝试时：

PREFIX qb: <http://purl.org/linked-data/cube#>
SELECT DISTINCT ?subject
WHERE 
{
  ?a qb:component ?subject .
  FILTER regex(?subject, "p", "i")
}

查询 returns table 没有行。有没有办法过滤获得的值？

Answer 1

我认为你应该在?subject上调用str函数，它不是一个字符串而是一个URI，所以首先你必须把它转换成一个字符串。

这应该有效：

PREFIX qb: <http://purl.org/linked-data/cube#>
SELECT DISTINCT ?subject
WHERE 
{
  ?a qb:component ?subject .
  FILTER regex(str(?subject), "p", "i")
}

在基本 sparql 查询中应用基于正则表达式的过滤器 returns 无结果

Applying regex-based filter in basic sparql query returns no results

sparql

opendata

问题