I am new to RDF and trying to build an expert system using it. I have created some tripples (using Blazegraph Turtle format).
PREFIX : <http://DMDData.com/>
PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
#Laser
:DMD_Laser :part_of :DMDProcess.
:DMD_Laser_velocity :parameter_of :DMD_Laser;
:min_speed "450"^^xsd:int;
:max_speed "750"^^xsd:int;
:positive_correlation_with :DMD_Layer_height.
:DMD_Laser_power :parameter_of :DMD_Laser;
:min_power "400"^^xsd:int;
:max_power "600"^^xsd:int;
:positive_correlation_with :DMD_Layer_height.
#PowderSupply
:DMD_PowderSupply :part_of :DMDProcess.
:DMD_PowderSupply_feedrate :parameter_of :DMD_PowderSupply;
:min_feedrate "0.09"^^xsd:float;
:max_feedrate "0.15"^^xsd:float;
:positive_correlation_with :DMD_Layer_height.
:DMD_PowderSupply_grainsize :parameter_of :DMD_PowderSupply;
:min_grainsize "1"^^xsd:float;
:max_grainsize "2"^^xsd:float.
:positive_correlation_with :DMD_Layer_height.
#Layer
:DMD_Layer :result_of :DMD_Laser;
:result_of :DMD_PowderSupply.
Instead of positive_correlation_with i want to relate the two objects with a numerical function. The final goal is to have an input (required layer height) and get the values for Laser Power, Laser velocity, powder feed rate as output (via a numerical calculation between the objects in the database)
Is that possible with RDF/SPRQL ?
Thank you
Related
I am trying to accomplish some relatively simple analysis with a specific graph.
In Marklogic SPARQL path are created with the following patterns
path+ (one or more duplicate path links)
path* (zero or more duplicate path links)
path? (zero or one path link)
path1/path2 (traversing through 2 different links)
From here, one analysis I would like to achieve is retrieving all nodes that fulfills a specific condition between node X and node Y. Based on this my query would be something like
?nodeX <nodeID> 1
?nodeY <nodeID> 250
?nodeX <nodeLink>* ?nodeY
Which does not really seem correct to me, as I don't think this allows me to retrieve the path linking nodeX to nodeY.
I would also like to know if it is possible to do things such as
Betweeness centrality which is a measure of the number of times a vertex is found between the shortest path of each vertex pair in a graph.
Closeness centrality which is a measure of the distance of one vertex to all other reachable vertices in the graph.
==Update==
Based on the suggestion I have managed to retrieve the path using the following query.
?nodeX <nodeID> "1"
?nodeY <nodeID> "250"
?nodeX <nodeLink>* ?v
?v ?p ?u
?u <nodeLink>* ?nodeY
When I attempted to do <p> | !<p> in my query an error occurred and stating ! was not a valid expression. However, I believe I can still do the same by using ?path which will accept any predicate.
I am trying to create a query using SPARQL on a ttl file where I have part of the graph representing links as follows:
Is it possible to search for the type Debit and get all the literals associated with its parent ie: R494Vol1D2, Salvo, Vassallo?
Do I need to use paths?
As AKSW correctly said, RDF is about directed graphs. So I created a small n-triples file based on your image of the graph. I assume that the dataset looks like this:
<http://natarchives.com.mt/deed/R494Vol1-D2> <http://purl.org/dc/terms/type> "Debit".
<http://natarchives.com.mt/deed/R494Vol1-D2> <http://purl.org/dc/terms/identifier> "R494Vol1D2".
<http://natarchives.com.mt/deed/R494Vol1-D2> <http://data.archiveshub.ac.uk/def/associatedWith> <http://natarchives.com.mt/person/person796>.
<http://natarchives.com.mt/person/person796> <http://xmlns.com/foaf/0.1/firstName> "Salvo".
<http://natarchives.com.mt/person/person796> <http://xmlns.com/foaf/0.1/family_name> "Vassallo".
Also I did not know the prefix locah but according to http://prefix.cc it stands for http://data.archiveshub.ac.uk/def/
So if this dataset is correct you could use the following query:
1 SELECT ?literal WHERE{
2 ?start <http://purl.org/dc/terms/type> "Debit".
3 ?start <http://data.archiveshub.ac.uk/def/associatedWith>* ?parent.
4 ?parent ?hasLiteral ?literal.
5 FILTER(isLiteral(?literal) && ?literal != "Debit" )
6 }
In line 2 we define the starting point of our path, which is every vertex that has the type "Debit". Then we look for all vertices that are connected to ?start with an edge labelled with <http://data.archiveshub.ac.uk/def/associatedWith>. These vertices are then bound to ?parent. After that we look for all triples that have ?parent as subject and store the object in ?literal. In Line 6 we filter everything that is not a literal or is "Debit" from ?literal resulting in the desired outcome.
If I modeled the direction of <http://data.archiveshub.ac.uk/def/associatedWith> wrongly, you could change line 3 of the query to:
?start ^<http://data.archiveshub.ac.uk/def/associatedWith>* ?parent
This would change the direction of the edge.
And to answer the question if you need to use paths: If you do not know how long the path of edges labeled with <http://data.archiveshub.ac.uk/def/associatedWith> will be, then in my opinion yes, you will have to use either * or + of property paths.
I'm struggling with the GeoSPARQL functions. I have two points defined in my ontology. Using this query I get them in my results:
PREFIX geo: <http://www.opengis.net/ont/geosparql#>
PREFIX geof: <http://www.opengis.net/def/function/geosparql/>
SELECT ?what ?met
WHERE {
?what geo:hasGeometry ?met .
FILTER geof:within( ?met ,"ENVELOPE(51.900991, 51.913594, 4.502206, 4.476328)"^^geo:wktLiteral ) .
}
http://www.example.org/POI#Headquater
http://www.example.org/POI#MiddenVanDeBrug
The question is why http://www.example.org/POI#ErasmusBrug is not part of the search result. Should it be possible to search for polygons within an envelop?
Which GeoSPARQL functions are available in Stardog? Any good example resource?
The ontology I use can be found here
The Stardog documentation for GeoSPARQL can be found here. For more specific support, please come visit us at Stardog Community.
I found out that there is an error in the log file of Stardog upon importing the data:
WARN 2017-12-14 08:31:30,989 [XNIO-1 task-24] com.complexible.stardog.spatial.io.StatementSourceGeospatialSource:parse(95): Failed to parse unknown/malformed shape POLYGON((4.476027 51.91137, 4.497099 51.911291, 4.497142 51.905307, 4.75813 51.905201, 4.476027 51.91137 )). Skipping this record
What could be wrong with this polygon?
I have loaded the geospatial data from geonames.org into Marklogic using RDF import.
When using the Query Console to explore the data, I see the data has been loaded into an xml document and looks like this:
<sem:triple>
<sem:subject>http://sws.geonames.org/2736540/</sem:subject>
<sem:predicate>http://www.w3.org/2003/01/geo/wgs84_pos#lat</sem:predicate>
<sem:object datatype="http://www.w3.org/2001/XMLSchema#string">40.41476</sem:object>
</sem:triple>
<sem:triple>
<sem:subject>http://sws.geonames.org/2736540/</sem:subject>
<sem:predicate>http://www.w3.org/2003/01/geo/wgs84_pos#long</sem:predicate>
<sem:object datatype="http://www.w3.org/2001/XMLSchema#string">-8.54304</sem:object>
</sem:triple>
I am able to do a SPARQL DESCRIBE and see data. Here is an example.
#prefix geonames: <http://www.geonames.org/ontology#> .
#prefix xs: <http://www.w3.org/2001/XMLSchema#> .
#prefix p0: <http://www.w3.org/2003/01/geo/wgs84_pos#> .
<http://sws.geonames.org/2736540/> geonames:parentCountry <http://sws.geonames.org/2264397/> ;
geonames:countryCode "PT"^^xs:string ;
p0:long "-8.54304"^^xs:string ;
geonames:featureCode <http://www.geonames.org/ontology#P.PPL> ;
geonames:parentADM1 <http://sws.geonames.org/2742610/> ;
geonames:parentFeature <http://sws.geonames.org/2742610/> ;
<http://www.w3.org/2000/01/rdf-schema#isDefinedBy> "http://sws.geonames.org/2736540/about.rdf"^^xs:string ;
a geonames:Feature ;
geonames:locationMap <http://www.geonames.org/2736540/pedreira-de-vilarinho.html> ;
geonames:name "Pedreira de Vilarinho"^^xs:string ;
geonames:nearbyFeatures <http://sws.geonames.org/2736540/nearby.rdf> ;
geonames:featureClass geonames:P ;
p0:lat "40.41476"^^xs:string .
I want to query over this data using SPARQL QUERY as my Query Type in a way where I can take advantage of the geospatial indexes that MarkLogic can create.
I have been having trouble with two aspects of this.
How to correctly create the geospatial indexes for the wgs84_pos#lat and wgs84_pos#long predicates?
How do I access those indexes from SPARQL QUERY?
I would like to have a sparql query that would be able to find subjects within some range of a Point.
=====================================
Followup:
After following David Ennis's Answer (Which worked nicely, thanks!) I ended up with this sample Xquery that was able to select data out of documents via geosearch and then use those IRI's in a sparql values query.
Example:
xquery version "1.0-ml";
import module namespace sem = "http://marklogic.com/semantics"
at "/MarkLogic/semantics.xqy";
let $matches := cts:search(//rdf:RDF,
cts:element-pair-geospatial-query (
fn:QName("http://www.geonames.org/ontology#","Feature"),
fn:QName("http://www.w3.org/2003/01/geo/wgs84_pos#", "lat"),
fn:QName ("http://www.w3.org/2003/01/geo/wgs84_pos#","long"),
cts:circle(10, cts:point(19.8,99.8))))
let $iris := sem:iri($matches//#rdf:about)
let $bindings := (fn:map(function($n) { map:entry("featureIRI", $n) }, $iris))
let $sparql := '
PREFIX wgs: <http://www.w3.org/2003/01/geo/wgs84_pos#>
SELECT *
WHERE {
?featureIRI wgs:lat ?lat;
wgs:long ?long.
}
'
return sem:sparql-values($sparql, $bindings)
This xquery queries the geospatial index, finds matching documents and then selects the IRI in the rdf:about attribute of the xml document.
It then maps over all of those IRIs and creates map entries that can be passed in the bindings parameter of the sem:sparql-values function.
I do not believe you can do what you want via just native SPARQL. Geospacial queries in any SPARQL implementation are extensions like geoSPARQL, Apache Jena geospacial queries etc.
My suggested approach in MarkLogic:
Insert the geonames subjects into MarkLogic as unmanaged triples (an XML or JSON document with embedded triples for each one)
In the same document, include the geo-spacial data in one of the acceptable MarkLogic formats. This essentially adds geo-spacial metadata to the triple since it is in the same fragment.
Add geo-spacial path-range-indexes for the geospacial data.
Use SPARQL inside of MarkLogic with a cts query restriction.
The Building Blocks for above:
Understanding unmanaged triples
Understanding Geo-spacial Region Types
Understanding Geo-spacial Indexes
Understanding Geo-spacial Queries
Understanding Semantics with cts search
Another approach to the final query could be the Optic API but I do not see how it would negate the need to do steps 1-3
I am trying to teach myself this weekend how to run API queries against a data source in this case data.gov. At first I thought I'd use a simple SQL variant, but it seems in this case I have to use SPARQL.
I've read through the documentation, downloaded Twinkle, and can't seem to quite get it to run. Here is an example of a query I'm running. I'm basically trying to find all gas stations that are null around Denver, CO.
PREFIX station: https://api.data.gov/nrel/alt-fuel-stations/v1/nearest.json?api_key=???location=Denver+CO
SELECT *
WHERE
{ ?x station:network ?network like "null"
}
Any help would be very much appreciated.
SPARQL is a graph pattern language for RDF triples. A query consists of a set of "basic graph patterns" described by triple patterns of the form <subject>, <predicate>, <object>. RDF defines the subject and predicate with URI's and the object is either a URI (object property) or literal (datatype or language-tagged property). Each triple pattern in a query must therefore have three entities.
Since we don't have any examples of your data, I'll provide a way to explore the data a bit. Let's assume your prefix is correctly defined, which I doubt - it will not be the REST API URL, but the URI of the entity itself. Then you can try the following:
PREFIX station: <http://api.data.gov/nrel...>
SELECT *
WHERE
{ ?s station:network ?network .
}
...setting the PREFIX to correctly represent the namespace for network. Then look at the binding for ?network and find out how they represent null. Let's say it is a string as you show. Then the query would look like:
PREFIX station: <http://api.data.gov/nrel...>
SELECT ?s
WHERE
{ ?s station:network "null" .
}
There is no like in SPARQL, but you could use a FILTER clause using regex or other string matching features of SPARQL.
And please, please, please google "SPARQL" and "RDF". There is lots of information about SPARQL, and the W3C's SPARQL 1.1 Query Language Recommendation is a comprehensive source with many good examples.