Re: match specific blank terms

> On Nov 24, 2017, at 7:21 AM, Anthony Durity <a.durity@umail.ucc.ie> wrote:
> 
> One last mail from me for now.
> 
> The alternative is that I avoid Array#include? and use something like
> terms.any?{|t| t == n }
> 
> Does anyone have any thoughts on the matter?

That’s pretty much what you’re left with, but with a large repository, could be very expensive. As a general rule, when using a SPARQL endpoint, you can use the form Ian suggested using FILTER, such as SELECT ?bn WHERE {?bn ?p ?o . FILTER(?bn == _:foo) } UNION {?s ?p2 ?_bn . FILTER(?bn == _:foo) }

When working with an in-memory repository, then terms.any? {|t| t.node? && t.iid == “foo”} is probably reasonable.

Gregg

> On 24 November 2017 at 12:05, Anthony Durity <a.durity@umail.ucc.ie <mailto:a.durity@umail.ucc.ie>> wrote:
> Ok, having looked at the code for RDF::Node I guess my question is. Why is #eql? different to #== for RDF::Node ? That gives me the situation where terms.last == n is true but terms.include?(n) gives me false.
> 
> On 24 November 2017 at 09:14, Ian Dickinson <i.j.dickinson@gmail.com <mailto:i.j.dickinson@gmail.com>> wrote:
> Hi Anthony,
> On Thu, Nov 23, 2017 at 10:13 PM, Anthony Durity <a.durity@umail.ucc.ie <mailto:a.durity@umail.ucc.ie>> wrote:
> > I was working under the impression that 'local scope' meant local to the
> > repo.
> >
> > Given that I have:
> > [
> > #<RDF::URI:0x2ac3bff25014 URI:https://dh.ucc.ie/entity/α54 <https://dh.ucc.ie/entity/%CE%B154>>,
> > #<RDF::URI:0x2ac3be8bc444 URI:http://www.wikidata.org/prop/direct/P31 <http://www.wikidata.org/prop/direct/P31>>,
> > #<RDF::URI:0x2ac3bff2c5d0 URI:http://www.wikidata.org/entity/Q187685 <http://www.wikidata.org/entity/Q187685>>,
> > #<RDF::URI:0x2ac3bff32b60 URI:https://dh.ucc.ie/entity/α55 <https://dh.ucc.ie/entity/%CE%B155>>,
> > #<RDF::URI:0x2ac3bff3f9f0 URI:https://dh.ucc.ie/entity/α56 <https://dh.ucc.ie/entity/%CE%B156>>,
> > #<RDF::URI:0x2ac3be892504 URI:https://dh.ucc.ie/entity/α57 <https://dh.ucc.ie/entity/%CE%B157>>,
> > #<RDF::Node:0x2ac3c025570c(_:g47253167721100)>,
> > #<RDF::Node:0x2ac3bf67d7b8(_:59)>,
> > #<RDF::Node:0x2ac3c0265d50(_:α60)>
> > ]
> > what's the best way to match the blank node 'α60' ? I tried “intern” just
> > there and it didn't work :/
> 
> I think it would be easier to offer advice if you could back up a bit
> and say what you're
> trying to achieve? As Gregg said, bNodes can be funny things, so the 'best
> way' to handle them tends to be a bit "well, it depends ..."!
> 
> Ian
> 
>