Constructing linked lists #349
justin2004
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Replies: 1 comment 5 replies
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Hi,
Warning:I haven't tried this.
You can maybe add the following triple pattern to the where clause
?root ?nextslotp ?nextcoords . FILTER (?nextslotp=fx:next(?slotp))
This should guarantee that the next slot exists.
Il mar 21 mar 2023, 17:17 Justin Dowdy ***@***.***> ha
scritto:
… Say we have an input file of lat/lon pairs like this:
[
[
39.60016098620319,
-103.2195004094572
],
[
39.59573278327245,
-103.2194553002621
],
[
39.59523919837688,
-103.21904029566723
],
[
39.595260054147836,
-103.21651418074191
],
[
39.59563075964951,
-103.21613900415993
],
[
39.59672976424879,
-103.21604796697486
],
[
39.60046508037667,
-103.21688247450476
],
[
39.60065213316467,
-103.21905219408251
],
[
39.60064628777271,
-103.2190446076504
]
]
And we want to string them together into a linked list structure.
At the moment I have this query:
PREFIX fx: <http://sparql.xyz/facade-x/ns/>PREFIX ex: <http://example.com/>PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>PREFIX xyz: <http://sparql.xyz/facade-x/data/>PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>CONSTRUCT
{
ex:Coordinate-Area_0 rdf:type ex:Coordinate-Area .
ex:Coordinate-Area_0 ex:start ex:_Coordinates_1 .
ex:Coordinate-Area_0 rdfs:label "Some location" .
?slot_iri rdf:type ex:Coordinate-Part .
?slot_iri ex:lat ?lat .
?slot_iri ex:lon ?lon .
?slot_iri ex:next ?next_slot_iri .
} WHERE
{ SERVICE <x-sparql-anything:>
{ fx:properties
fx:location "/app/ll.json"
{ ?root rdf:type fx:root ;
?slotp ?coords .
?coords rdf:_1 ?lat ;
rdf:_2 ?lon
BIND(replace(str(?slotp), concat(str(rdf:), "_"), "") AS ?slot_num)
BIND(( xsd:int(?slot_num) + 1 ) AS ?next_slot_num)
BIND(IRI(concat(str(ex:), "_Coordinates_", ?slot_num)) AS ?slot_iri)
BIND(IRI(concat(str(ex:), "_Coordinates_", str(?next_slot_num))) AS ?next_slot_iri)
}
}
}
which produces these triples:
@Prefix ex: <http://example.com/> .@Prefix fx: <http://sparql.xyz/facade-x/ns/> .@Prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .@Prefix rdfs: <http://www.w3.org/2000/01/rdf-schema#> .@Prefix xsd: <http://www.w3.org/2001/XMLSchema#> .@Prefix xyz: <http://sparql.xyz/facade-x/data/> .
ex:_Coordinates_2 rdf:type ex:Coordinate-Part ;
ex:lat "39.59573278327245"^^xsd:double ;
ex:lon "-103.2194553002621"^^xsd:double ;
ex:next ex:_Coordinates_3 .
ex:_Coordinates_7 rdf:type ex:Coordinate-Part ;
ex:lat "39.60046508037667"^^xsd:double ;
ex:lon "-103.21688247450476"^^xsd:double ;
ex:next ex:_Coordinates_8 .
ex:Coordinate-Area_0 rdf:type ex:Coordinate-Area ;
rdfs:label "Some location" ;
ex:start ex:_Coordinates_1 .
ex:_Coordinates_5 rdf:type ex:Coordinate-Part ;
ex:lat "39.59563075964951"^^xsd:double ;
ex:lon "-103.21613900415993"^^xsd:double ;
ex:next ex:_Coordinates_6 .
ex:_Coordinates_3 rdf:type ex:Coordinate-Part ;
ex:lat "39.59523919837688"^^xsd:double ;
ex:lon "-103.21904029566723"^^xsd:double ;
ex:next ex:_Coordinates_4 .
ex:_Coordinates_8 rdf:type ex:Coordinate-Part ;
ex:lat "39.60065213316467"^^xsd:double ;
ex:lon "-103.21905219408251"^^xsd:double ;
ex:next ex:_Coordinates_9 .
ex:_Coordinates_1 rdf:type ex:Coordinate-Part ;
ex:lat "39.60016098620319"^^xsd:double ;
ex:lon "-103.2195004094572"^^xsd:double ;
ex:next ex:_Coordinates_2 .
ex:_Coordinates_6 rdf:type ex:Coordinate-Part ;
ex:lat "39.59672976424879"^^xsd:double ;
ex:lon "-103.21604796697486"^^xsd:double ;
ex:next ex:_Coordinates_7 .
ex:_Coordinates_4 rdf:type ex:Coordinate-Part ;
ex:lat "39.595260054147836"^^xsd:double ;
ex:lon "-103.21651418074191"^^xsd:double ;
ex:next ex:_Coordinates_5 .
ex:_Coordinates_9 rdf:type ex:Coordinate-Part ;
ex:lat "39.60064628777271"^^xsd:double ;
ex:lon "-103.2190446076504"^^xsd:double ;
ex:next ex:_Coordinates_10 .
Which is basically the desired output except for this single triple:
ex:_Coordinates_9 ex:next ex:_Coordinates_10 .
Anyone have an idea about how to prevent that triple from getting created?
It would be easy to fix in a post-processing step but I am curious if we
could prevent it from getting created in that single query.
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5 replies
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@luigi-asprino It worked! Clever. |
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@luigi-asprino Ah, I spoke a little soon. It looks like that causes it to not produce these triples: ex:_Coordinates_9 rdf:type ex:Coordinate-Part ;
ex:lat "39.60064628777271"^^xsd:double ;
ex:lon "-103.2190446076504"^^xsd:double .since it is the last in the chain |
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True.. well.. |
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Can't you wrap it in an OPTIONAL clause? (not tried) OPTIONAL { ?root ?nextslotp ?nextcoords . FILTER (?nextslotp=fx:next(?slotp)) } |
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ah, that union did it, @luigi-asprino . nice! |
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Say we have an input file of lat/lon pairs like this:
[ [ 39.60016098620319, -103.2195004094572 ], [ 39.59573278327245, -103.2194553002621 ], [ 39.59523919837688, -103.21904029566723 ], [ 39.595260054147836, -103.21651418074191 ], [ 39.59563075964951, -103.21613900415993 ], [ 39.59672976424879, -103.21604796697486 ], [ 39.60046508037667, -103.21688247450476 ], [ 39.60065213316467, -103.21905219408251 ], [ 39.60064628777271, -103.2190446076504 ] ]And we want to string them together into a linked list structure.
At the moment I have this query:
which produces these triples:
Which is basically the desired output except for this single triple:
Anyone have an idea about how to prevent that triple from getting created? It would be easy to fix in a post-processing step but I am curious if we could prevent it from getting created in that single query.
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