Re: [Bigdata-developers] Geonames and Blazegraph Geospatial index

[Jem R. <jem...@ft...>]

Hi Michael,

I will take a look at WKT and Stas's implementation.

Re:deleting the single-component literals these are expected and are part
of the geonames ontology so I will leave these.

Thanks!
Jem

On 25 July 2016 at 19:52, Michael Schmidt <ms...@me...> wrote:

> Hi Jem,
>
> we are aware of this limitation and have been discussing this use case
> previously, but (as you guessed) indexing of such “distributed” coordinates
> is currently not implemented. So for now there’s no way around the
> transformation (you may, however, want to consider deleting the
> single-component literals when creating the composed literals, if that’s an
> option for you).
>
> As a side note: there are also standards-based binary coordinate formats
> in which you could transform the literals. For instance, Wikidata is using
> WKT literals, see the POINT datatype in
> https://en.wikipedia.org/wiki/Well-known_text, which could easily be used
> in combination with a customer geospatial LiteralSerializer.
>
> Best,
> Michael
>
> On 25 Jul 2016, at 17:14, Jem Rayfield <jem...@ft...> wrote:
>
> I guess I could invoke a sparql update as follows:
>
> INSERT {
>   ?s <http://jems/latlong> ?latlong
> }
> WHERE {
>  ?s <http://www.w3.org/2003/01/geo/wgs84_pos#lat> ?lat ;
>     <http://www.w3.org/2003/01/geo/wgs84_pos#long> ?long .
>  BIND(STRDT(STR(CONCAT(?lat, "#", ?long)), <
> http://jems/custom/latlong/literaltype>) AS ?latlong)
> }
>
> However this will create many millions of essentially redundant statements?
>
> Question, re: multiple predicate index still stands.
>
> Cheers
> Jem
>
>
> On 25 July 2016 at 15:14, Jem Rayfield <jem...@ft...> wrote:
>
>> Hello,
>>
>> I would like to index geonames lat/long using Blazegraphs geospatial
>> index.
>>
>> Geonames lat/longs are provided in the following flavour of RDF:
>>
>> <http://sws.geonames.org/4667981/> <
>> http://www.w3.org/2003/01/geo/wgs84_pos#lat> "35.79787" .
>> <http://sws.geonames.org/4667981/> <
>> http://www.w3.org/2003/01/geo/wgs84_pos#long> "-83.44683" .
>>
>> I was wondering if anyone has already worked on Custom Geospatial Data
>> types, vocabularies etc for Geonames in Blazegraph ?
>>
>>
>> It appears that one would need flatten the objects into a single
>> multidimensional literal for indexing?
>>
>> <http://sws.geonames.org/4667981/> somenamespace:latlong
>> "35.79787#-83.44683"
>>
>> With the configuration and definition of a new literal type?
>>
>> I am wondering if its possible to index on multiple known predicates
>> rather than multidimensional literals with extended data types?
>>
>>
>> Cheers
>> --
>> *Jem Rayfield*
>> Head of Solution Architecture
>> Technology
>>
>> +44 (0)7709 332482
>> Number One Southwark Bridge, London SE1 9HL
>>
>>
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>>
>
>
>
> --
> *Jem Rayfield*
> Head of Solution Architecture
> Technology
>
> +44 (0)7709 332482
> Number One Southwark Bridge, London SE1 9HL
>
>
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-- 
*Jem Rayfield*
Head of Solution Architecture
Technology

+44 (0)7709 332482
Number One Southwark Bridge, London SE1 9HL


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<http://www.linkedin.com/company/financial-times>
<https://plus.google.com/+FinancialTimes/posts>
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