-------------------------------------------------- Fadi Maali PhD student @ Insight Galway (formerly DERI) Irish Research Council Embark Scholarship holder http://www.deri.ie/users/fadi-maali
On 28 Oct 2013, at 20:37, Jeff Mixter <[email protected]> wrote: > A Response and a follow-up question, > > As Kingsley mentioned suggested, I have been able to get the reconciliation > service to work using LOD Refine with DBpedia and Freebase. If you want, I > would be more than happy to set up a Google Hangouts and walk you through the > process. > > I have experienced some problems, but it was when I tried to reconcile > against my own 4Store instance. Which leads me to my own question. LOD > Refine's standard SPARQL query is extremely poorly constructed and when > querying large datasets (using 4Store) my requests always time out. The > dataset is a VIAF.nt data dump and consists of ~476 Million triples. I have > tried increasing the "soft limit" of the 4store server, but all this seems to > do is cause them to take longer to fail. I do not want to spend the money on > a Virtuoso instance, since I am just using this dataset for experimentation. > Using Fiddler I was able to track the actual http request made by the > Reconciliation and noticed an oddity in the standard query. The issue with > the standard LOD query is that they declare that the parameter being sent in > the query is a string (str) even though that should be obvious (see below): > > > Exact Match Search > PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> > PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> > > SELECT ?entity > WHERE {?entity <http://xmlns.com/foaf/0.1/name> ?label > FILTER ( str(?label) = "Hunter, Virginia, 1921-2011") > } > This is needed to match language-tagged and type-tagged literals. > Character by Character string match > PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> > PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#> > > SELECT ?entity ?label1 > WHERE {?entity <http://xmlns.com/foaf/0.1/name> ?label1 > FILTER regex(str(?label1), "Hunter, Virginia, 1921-2011", "i") > } > > When using the http SPARQL endpoint, I can remove the str parameter and > retrieve back results. This is true both for direct queries (exact matches) > as well as string matches (close match). Does anyone have any way to easily > change the syntax of the SPARQL query that is sent out? This seems as a problem with 4store to me. To change the SPARQL you can edit this: https://github.com/fadmaa/grefine-rdf-extension/blob/master/src/org/deri/grefine/reconcile/rdf/factories/PlainSparqlQueryFactory.java change the static strings at the bottom of the file. Regards, Fadi > > Thanks, > > Jeff Mixter > [email protected] > [email protected] > 440-773-9079 > > > On Mon, Oct 28, 2013 at 3:44 PM, Kingsley Idehen <[email protected]> > wrote: > On 10/28/13 2:59 PM, Hugh Glaser wrote: > Unfortunately I’ve not been a regular user, so it is probably my stupidity. > Basically, I go through the Reconcile process using the Freebase Reconcile > service, but it doesn’t find anything to reconcile, even though I have fixed > it so that there is an entry that has exactly the same text as the Freebase > entry title. > It just shows as if there are no positive results. > I try clicking on the search for match after that, but it never comes back, > which makes me wonder. > > I've played with LOD Refine and successfully used reconciliation via Sindice, > DBpedia and a variety of Entity Extraction Services (e.g., DBpedia Spotlight, > Spaziodati, and Zemanta). By reconciliation I mean: > > 1. selecting a column > 2. choosing the reconciliation or entity extraction menu options > 3. getting back Linked Data URIs . > > With the reconciliation in place, I can then: > 1. leverage the Linked Data URIs from the reconciliation process when > constructing RDF skeletons (mappings from tabular to property graph based > data representation) > 5. use the RDF skeleton to generate a Turtle document. > > In my recent experience, there are times when the system has just stopped > working without any specific indication as to why e.g., imported (or bound) > prefixes aren't recognized when constructing RDF mapping skeletons etc.. > > Maybe you could share your project file (via their project export option) and > others could shed light on what might be going wrong etc.. > > > Kingsley > > > On 28 Oct 2013, at 18:53, John Erickson <[email protected]> wrote: > > Hugh, I wonder if you could be more specific regarding the troubles > you had with OpenRefine? > > One of our students also had trouble, and I'm wondering if it might be > the same problem. > > Like you, reconciliation with Refine has worked for me in the past but > I haven't tried the same process using OpenRefine... > > On Mon, Oct 28, 2013 at 2:41 PM, Hugh Glaser <[email protected]> wrote: > Hi. > I’m not sure where to ask, so I’ll try my friends here. > I was having a go at OpenRefine yesterday, and I can’t get it to reconcile, > try as I might - I have even watched the videos again. > I’m doing what I remember, but it is a while ago. > Are there others currently using it successfully? > Or is it possibly a Mavericks (OSX) upgrade thing, which I did recently. > Cheers > -- > Hugh > > > > -- > John S. Erickson, Ph.D. > Director, Web Science Operations > Tetherless World Constellation (RPI) > <http://tw.rpi.edu> <[email protected]> > Twitter & Skype: olyerickson > -- > Hugh > 023 8061 5652 > > > > > > > -- > > Regards, > > Kingsley Idehen > Founder & CEO > OpenLink Software > Company Web: http://www.openlinksw.com > Personal Weblog: http://www.openlinksw.com/blog/~kidehen > Twitter/Identi.ca handle: @kidehen > Google+ Profile: https://plus.google.com/112399767740508618350/about > LinkedIn Profile: http://www.linkedin.com/in/kidehen > > > > > > > > > -- > Jeff Mixter > [email protected] > 440-773-9079
