Processing Multivalue References in CSV

[tobiasschweizer]

Hi there

I am trying to create linking property values from a string with concatenated foreign keys in a CSV.

CSV data source: https://data.snf.ch/Exportcsv/Person.csv

mapping:

@prefix csvw: <http://www.w3.org/ns/csvw#> .
@prefix rr: <http://www.w3.org/ns/r2rml#>.
@prefix rml: <http://semweb.mmlab.be/ns/rml#>.
@prefix ql: <http://semweb.mmlab.be/ns/ql#>.
@prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
@prefix schema: <http://schema.org/>.
@prefix wgs84_pos: <http://www.w3.org/2003/01/geo/wgs84_pos#lat>.
@prefix gn: <http://www.geonames.org/ontology#>.
@prefix carml: <http://carml.taxonic.com/carml/> .
@prefix fnml: <http://semweb.mmlab.be/ns/fnml#> .
@prefix grel: <http://users.ugent.be/~bjdmeest/function/grel.ttl#> .
@prefix fno: <https://w3id.org/function/ontology#> .
@base <http://example.com/ns#>.

<#LogicalSourcePerson> a rml:BaseSource ;
  rml:source <#CSVW_sourcePerson> ;
  rml:referenceFormulation ql:CSV .

<#CSVW_sourcePerson> a csvw:Table;
   csvw:url "Person.csv" ;
   csvw:dialect [ a csvw:Dialect;
       csvw:delimiter ";"
   ] .

<#PersonMapping> a rr:TriplesMap;
  rml:logicalSource <#LogicalSourcePerson> ;

  rr:subjectMap [
    rr:template "http://snf.ch/person/{PersonNumber}";
    rr:class schema:Person
  ] ;

  rr:predicateObjectMap [
    rr:predicate schema:memberOf ;
    rr:objectMap <#JoinMap> ;
  ] ;

  rr:predicateObjectMap [
    rr:predicate schema:givenName ;
    rr:objectMap [
      rml:reference "FirstName"
    ]
  ] ;

  rr:predicateObjectMap [
    rr:predicate schema:familyName ;
    rr:objectMap [
      rml:reference "Surname"
    ]
  ] .

<#JoinMap>
    fnml:functionValue [
        rr:predicateObjectMap [
            rr:predicate fno:executes ;
            rr:objectMap [ rr:constant grel:array_join ]
        ];
        rr:predicateObjectMap [
            rr:predicate grel:p_array_a ;
            rr:objectMap [ rr:constant "http://snf.ch/project/" ]
        ];
        rr:predicateObjectMap [
            rr:predicate grel:p_array_a ;
            rr:objectMap <#FunctionMap>
        ];
    ] .


# https://stackoverflow.com/questions/53715353/converting-a-csv-to-rdf-where-one-column-is-a-set-of-values
<#FunctionMap>
    fnml:functionValue [
        rml:logicalSource <#LogicalSourceGrant>;
        rr:predicateObjectMap [
            rr:predicate fno:executes;
            rr:objectMap [
                rr:constant grel:string_split # function to use
            ];
        ];
        rr:predicateObjectMap [
            rr:predicate grel:valueParameter;
            rr:objectMap [
                rml:reference "ResponsibleApplicantGrantNumber" # input string: concatenated foreign keys
            ];
        ];
        rr:predicateObjectMap [
            rr:predicate grel:p_string_sep;
            rr:objectMap [
                rr:constant ";";
            ];
        ];
    ].

result:

"http://schema.org/memberOf" : [ {
    "@value" : "http://snf.ch/project/111925667315583634468"
  }

expected result:

  "http://schema.org/memberOf" : [ {
    "@value" : "http://snf.ch/project/111925"
  }, {
    "@value" : "http://snf.ch/project/34468"
  }, {
    "@value" : "http://snf.ch/project/55836"
  }, {
    "@value" : "http://snf.ch/project/66731"
  } ]

For more details, see kg-construct/rml-questions#15 (reply in thread)

[DylanVanAssche]

The problem is that the same delimiter is used for multi values as columns.
To avoid confusing, the values are quoted. However, the OpenCSV library in the RMLMapper does not pick this up it seems.

[tobiasschweizer]

The problem is that the same delimiter is used for multi values as columns. To avoid confusing, the values are quoted. However, the OpenCSV library in the RMLMapper does not pick this up it seems.

Yes, this is how I understood this works in CSV. The quoting ist like escaping characters that have a special meaning (meta chars). Maybe we could look at the library you mentioned or create an issue in their repo. Let my know if I can be of any assistance.