Sparql s、 谢谢，我明天晚些时候会查，现在我要做另一件新事情，我会问一个问题 @prefix rs: <http://example.org/rs#> @prefix bo: <http://example.org/bo#> @prefi

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s、 谢谢，我明天晚些时候会查，现在我要做另一件新事情，我会问一个问题

@prefix rs: <http://example.org/rs#>
@prefix bo: <http://example.org/bo#>
@prefix rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
@prefix xsd: <http://www.w3.org/2001/XMLSchema#>

rs:user1 rs:hasRated [rs:by "1.0"^^xsd:float ; rs:item bo:animalFarm] .

rs:user2 rs:hasRated [rs:by "0.9"^^xsd:float ; rs:item bo:animalFarm] .

rs:user3 rs:hasRated [rs:by "0.9"^^xsd:float ; rs:item bo:animalFarm] .

rs:user4 rs:hasRated [rs:by "0.5"^^xsd:float ; rs:item bo:book3] .

rs:user5 rs:hasRated [rs:by "0.6"^^xsd:float ; rs:item bo:book3] .

rs:user6 rs:hasRated [rs:by "0.8"^^xsd:float ; rs:item bo:algorithem1] .

rs:user7 rs:hasRated [rs:by "0.9"^^xsd:float ; rs:item bo:algorithem1] .

rs:user8 rs:hasRated [rs:by "0.3"^^xsd:float ; rs:item bo:book4] .

PREFIX  bo:   <http://example.org/bo#>
PREFIX  xsd:  <http://www.w3.org/2001/XMLSchema#>
PREFIX  rdf:  <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX  rs:   <http://example.org/rs#>
select ?item (AVG(?ratingValue) as ?avg) (COUNT(*) as ?count) 
{
    ?user rs:hasRated [ rs:item ?item ;  rs:by ?ratingValue ] .
}
group by ?item 

bo:book3                 (0.55/(0.55 + 0.93333334 + 0.85 + 0.3 ))   (2/(2 + 3 + 2 + 1))