[R] Using R to convert RDF/XML to

[Bill Dunlap]

This is the sort of thing that you should first ask the package maintainer
about; there is an error in the rdf method for write_nquads:

> rdflib:::write_nquads.rdf
function (x, file, ...)
{
    rdf_serialize(rdf, file, "nquads", ...)
}

I suspect that the first argument to rdf_serialize should be 'x', not 'rdf'.

Another error in the package is that this function isn't tested.

-Bill


On Fri, Dec 31, 2021 at 6:19 AM Evans, Richard K. (GRC-H000) via R-help <
r-help using r-project.org> wrote:

> Hello R community,
>
> I am a novice R enthusiast trying to use R to convert an RDFdump file [1]
> from Semantic Mediawiki [2] into something that can be natively imported by
> GePhi [3] for graph visualization. The SMW RDFdump file is formatted as
> RDF/XML and I have found the R package "rdflib" [4] and am able to read the
> RDF/XML file into R as an "rdf" object, but it is not clear to me how to
> save the "rdf_serialize" function output to a new file.
>
> What I have so far is:
> library(rdflib)
> NewRDF <- tempfile( "TempFile", fileext = ".nq" )
> MyRDF <- rdf_parse( "MyRDFdumpFile.txt" )
> rdf_serialize( MyRDF, NewRDF, format = "nquads"  )
> write_nquads( MyRDF, NewRDF )
>
> ..but this results in the error: "Error: object of type 'closure' is not
> subsettable"
>
> I will keep struggling with this to learn what I need to learn, but any
> advice to help make quick work of this would be much appreciated.
>
> Thank you in advance.
> /Rich
>
> [1]
> https://www.semantic-mediawiki.org/wiki/Help:Maintenance_script_dumpRDF.php
> [2]
> https://www.semantic-mediawiki.org/wiki/Help:Introduction_to_Semantic_MediaWiki
> [3] https://gephi.org/
> [4] https://cran.r-project.org/web/packages/rdflib/rdflib.pdf
>
> - Richard Evans, NASA GRC - Armstrong Test Facility
>   mailto://richard.k.evans@nasa.gov
>   http://www.linkedin.com/in/rkevans
>
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