Refine the relationship between tune_set and tune (TheSession)

[candlecao]

1. Embody rdf:list in programing.

Check if the sequence of tunes are right in accordance with that in the CSV files.

2. Check the redundancy of the set.csv file.
3. Check how to query a list in SPARQL.

Follow/Refer to #142

[candlecao]

3. Check how to query a list in SPARQL.

--If I have a graph with data:

<https://thesession.org/members/1/sets/1> <https://thesession.org/tunes> (
      <https://thesession.org/tunes/560>
      <https://thesession.org/tunes/563>
      <https://thesession.org/tunes/570>
) .

then if I want to check the third value of the list of values for the property <https://thesession.org/tunes>,
the code can be:

SELECT ?thirdValue
WHERE {
  <https://thesession.org/members/1/sets/1> <https://thesession.org/tunes> ?list .
  ?list rdf:rest/rdf:rest/rdf:first ?thirdValue .
}

[fujinaga]

Are you not supposed to define the predicate that precede the rdf:List of objects that the predicate is expecting a list? Did you do that?

[fujinaga]

A simpler solution is to use “rdf:type rdf:List” as the predicate, instead.

[candlecao]

Hi, Ich. I don't quite understand your meaning.
I know rdf:list is a class.
May I put it this way:

1. Bunch 1

<https://thesession.org/members/1/sets/1> <https://thesession.org/tunes> (
      <https://thesession.org/tunes/560>
      <https://thesession.org/tunes/563>
      <https://thesession.org/tunes/570>
) .

--This above is equivalent with:

2. Bunch 2

@prefix ex: <http://example.org/> .
ex:playlist rdf:type rdf:List ;# Hi Ich, This might be what you mentioned--the simpler solution.
  rdf:first <https://thesession.org/tunes/560> ;
  rdf:rest [
    rdf:first <https://thesession.org/tunes/563> ;
    rdf:rest [
      rdf:first <https://thesession.org/tunes/570> ;
      rdf:rest rdf:nil
    ]
  ] .
<https://thesession.org/members/1/sets/1> <https://thesession.org/tunes> ex:playlist.

To conclude
A concise way to define lists is using parentheses (...) as shown in Bunch 1.
Let's trial this way:

If you import Bunch 1 to Virtuoso, then execute query like
2.1

select * where {?s <https://thesession.org/tunes> ?o}

the result is:

2.2

select * where {?s ?p ?o}

the result is:

[fujinaga]

I commented because you said you were having problems finding the "third value of the list." You also posted on Slack a similar question, which I can't find now. Is this issue resolved now?

[candlecao]

Finding the "third value of the list." is already solved. See:

SELECT ?thirdValue
WHERE {
  <https://thesession.org/members/1/sets/1> <https://thesession.org/tunes> ?list .
  ?list rdf:rest/rdf:rest/rdf:first ?thirdValue .# If it's the third value, we use "rdf:rest/rdf:rest/rdf:first"; if fourth, use "rdf:rest/rdf:rest//rdf:rest/rdf:first"
}

(quoted from above)
Sorry, but I didn't post on Slack any similar question.

This issue is not solved yet. Yueqiao is trying programing to generate list from CSV.