I am using the following query
PREFIX dct: <http://purl.org/dc/terms/>
SELECT ?subject WHERE {
?concept rdfs:label 'Exoskeleton'#en ;
^dct:subject ?subject .
}
ORDER BY ?subject
This doesn't give me any results. However, the rdfs:label exists. (See http://dbpedia.org/page/Exoskeleton.)
On querying with a different label, it works :
PREFIX dct: <http://purl.org/dc/terms/>
SELECT ?subject WHERE {
?concept rdfs:label 'Machine learning'#en ;
^dct:subject ?subject .
}
ORDER BY ?subject
The above query works and gives me the results. (See http://dbpedia.org/page/Machine_learning.)
What do I change, such that the first query works too?
The dct:subject predicate is used between a page and a category it belongs to. So, your second query is giving you results that are in Category:Machine learning. But since there is no Category:Exoskeleton, your first query gives you no results. This also means the two pages you liked to are irrelevant to your queries.
I don't know how to change the first query so that it works, because I don't understand what would "working" entail.
Devil is in the details:
PREFIX dct: <http://purl.org/dc/terms/>
SELECT ?concept WHERE {
?concept rdfs:label 'Machine learning'#en.
}
ORDER BY ?concept
Returns two results:
http://dbpedia.org/resource/Category:Machine_learning
http://dbpedia.org/resource/Machine_learning
While Exoskeleton has no corresponding concept:
http://dbpedia.org/resource/Exoskeleton
Thus your inverse property path finds resources under a http://dbpedia.org/resource/Category:Machine_learning concept but not under a http://dbpedia.org/resource/Machine_learning or http://dbpedia.org/resource/Exoskeleton pages.
If you drop the inverse modifier,
PREFIX dct: <http://purl.org/dc/terms/>
SELECT ?subject WHERE {
?concept rdfs:label 'Exoskeleton'#en ;
dct:subject ?subject .
}
ORDER BY ?subject
Will return the categories (subject) for the concepts under a given label.
Related
i want to display the countries with their net value/income or something similiar through accessing the data through DBPedia. and further insert them into an already created table.
Unfortunately i dont get any results with my code.
Try the following query to list the type of entities that has a dbp:income as a property. you will notice that dbo:Country is not the list, that's why the result you got was empty.
prefix dbp: <http://dbpedia.org/property/>
select distinct ?type
where {
?s a ?type.
?s dbp:income ?income
}
My suggestion is to use dbp:gdpNominal instead of the dbp:income property in your query :
prefix dbp: <http://dbpedia.org/property/>
prefix dbo: <http://dbpedia.org/ontology/>
select distinct ?country_name ?income
where {
?country a dbo:Country.
?country rdfs:label ?country_name. FILTER (lang(?country_name) = 'en')
?country dbp:gdpNominal ?income.
}
I'm doing sparql query in this site.
It gives me an empty result, what is wrong with my query?
prefix foaf: <http://xmlns.com/foaf/0.1/>
select * where {
?s rdf:type foaf:Person.
} LIMIT 100
This query is ok, but when I add the second pattern, I got empty result.
?s foaf:name 'Abraham_Robinson'.
prefix foaf: <http://xmlns.com/foaf/0.1/>
select * where {
?s rdf:type foaf:Person.
?s foaf:name 'Abraham_Robinson'.
} LIMIT 100
How to correct my query so the result includes this record:
http://dbpedia.org/resource/Abraham_Robinson
I guess Kingsley misread this as a freetext search, rather than a simple string comparison.
The query Kingsley posted and linked earlier delivers no solution, for the same reasons as the original query failed, as identified in the comment by AKSW, i.e. --
foaf:name values don't generally replaces spaces with underscores as in the original value; i.e., 'Abraham_Robinson' should have been 'Abraham Robinson'
foaf:name strings are typically langtagged, and it is in this case, so that actually needs to be 'Abraham Robinson'#en
Incorporating AKSW's fixes with this line ?s foaf:name 'Abraham Robinson'#en., the query works.
All that said -- you may prefer an alternative query, which will deliver results whether or not the foaf:name value is langtagged and whether or not the spaces are replaced by underscores. This one is Virtuoso-specific, and produces results faster because the bif:contains function uses its free-text indexes, would be --
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT *
WHERE
{
?s rdf:type foaf:Person ;
foaf:name ?name .
?name bif:contains "'Abraham Robinson'" .
}
LIMIT 100
Generic SPARQL using a REGEX FILTER works against both Virtuoso and other RDF stores, but produces results more slowly because REGEX does not leverage the free-text indexes, as in --
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT *
WHERE
{
?s rdf:type foaf:Person ;
foaf:name ?name .
FILTER ( REGEX ( ?name, 'Abraham Robinson' ) ) .
}
LIMIT 100
The following query should work. Right now it isn't working due to a need to refresh the text index associated with this instance (currently in progress):
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT * where {
?s rdf:type foaf:Person.
?s foaf:name "'Abraham Robinson'".
}
LIMIT 100
Note how the phrase is placed within single-quotes that are within double-quotes.
If the literal content is language-tagged, as is the case in DBpedia the exact-match query would take the form (already clarified in #TallTed's response):
PREFIX foaf: <http://xmlns.com/foaf/0.1/>
SELECT * where {
?s rdf:type foaf:Person.
?s foaf:name 'Abraham Robinson'#en.
}
LIMIT 100
This SPARQL Results Page Link should produce a solution when the index update completes.
I am trying to run the following sparql query :
PREFIX dct: <http://purl.org/dc/terms/>
select distinct ?subject
where
{
?concept rdfs:label 'Artificial intelligence'#en .
?concept ^dct:subject ?subject .
}
LIMIT 100
When I run this on dbpedia's public server, I get the following results :
http://dbpedia.org/sparql?default-graph-uri=&query=PREFIX++dct%3A++%3Chttp%3A%2F%2Fpurl.org%2Fdc%2Fterms%2F%3E+select+distinct+%3Fsubject+where+%7B+%3Fconcept+rdfs%3Alabel+%27Artificial+intelligence%27%40en+.+%3Fconcept+%5Edct%3Asubject+%3Fsubject+.+%7D++LIMIT+100&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on
However, running the same query on a locally hosted instance of dbpedia, yields : http://34.195.108.80:8891/sparql?default-graph-uri=&query=PREFIX++dct%3A++%3Chttp%3A%2F%2Fpurl.org%2Fdc%2Fterms%2F%3E+select+distinct+%3Fsubject+where+%7B+%3Fconcept+rdfs%3Alabel+%27Artificial+intelligence%27%40en+.+%3Fconcept+%5Edct%3Asubject+%3Fsubject+.+%7D++LIMIT+100&format=text%2Fhtml&CXML_redir_for_subjs=121&CXML_redir_for_hrefs=&timeout=30000&debug=on
Why is there a discrepancy in the answers to the point where it's entirely different?
I don't know what do you mean by "different", but without ORDER BY results will be returned more or less randomly simply influenced by the underlying system. There is even no guarantee that running the same query twice on the same server will return the results in the same order. Your query returns only 100 due to the LIMIT 100
The total number of results is the same for both queries, 271:
PREFIX dct: <http://purl.org/dc/terms/>
SELECT count(distinct ?subject) WHERE {
?concept rdfs:label 'Artificial intelligence'#en ;
? ^dct:subject ?subject .
}
For comparison, you have to use ORDER BY:
PREFIX dct: <http://purl.org/dc/terms/>
SELECT ?subject WHERE {
?concept rdfs:label 'Artificial intelligence'#en ;
^dct:subject ?subject .
}
ORDER BY ?subject
I am trying to get abstract using Sqarql with dbpedia datasets.
When I am running the following query on Virtuoso,
PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>
SELECT DISTINCT ?abstract WHERE {
[ rdfs:label ?name
; dbpedia-owl:abstract ?abstract
] .
FILTER langMatches(lang(?abstract),"en")
VALUES ?name { "London"#en }
}
LIMIT 10
I am getting the result, however if I modify the name to say 'Gokarna' which is a south indian tourist spot, I am not getting any data. However I do see the resource page online on dbpedia for Gokarna(http://dbpedia.org/page/Gokarna,_India). What am I doing wrong? I need to get similar data for close to 800 indian places.
When you use values, you'd get only those that exactly match your string. For Gokarna, that would work for #de, #it, #fr, but not for #en, as there the label is different, as you can see also from the previous answer.
I would suggest to use contains, instead of values:
PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>
SELECT DISTINCT ?abstract WHERE {
[ rdfs:label ?name
; dbpedia-owl:abstract ?abstract
] .
FILTER langMatches(lang(?abstract),"en")
FILTER langMatches(lang(?name),"en")
FILTER CONTAINS (?name, "Gokarna" )
}
LIMIT 10
I am not that experience with Sqarql but as much i can see in your code and checked with dbpedia library...
it is not just Gokarna. it is "Gokarna,_India".
This should work..
PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>
SELECT DISTINCT ?abstract WHERE {
[ rdfs:label ?name
; dbpedia-owl:abstract ?abstract
] .
FILTER langMatches(lang(?abstract),"en")
VALUES ?name { "Gokarna,_India"#en }
}
LIMIT 10
If you look through the DBpedia page for Gokarna, India that you linked to, you'll notice that its rdfs:label is "Gokarna, India". But its foaf:name is just "Gokarna". This would mean you should modify your query to:
PREFIX dbpedia-owl: <http://dbpedia.org/ontology/>
SELECT DISTINCT ?abstract WHERE {
[ foaf:name ?name
; dbpedia-owl:abstract ?abstract
] .
FILTER langMatches(lang(?abstract),"en")
VALUES ?name { "Gokarna"#en }
}
LIMIT 10
Though this will return other Gokarnas too: Gokarna, Nepal, Gokarna, Bangladesh and Gokarna (film). If you want to remove these, you will have to figure out another filter (possibly dbo:country dbr:India).
I'm executing this query in http://dbpedia.org/snorql/:
Query:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX type: <http://dbpedia.org/class/yago/>
PREFIX prop: <http://dbpedia.org/property/>
SELECT ?country_name ?population
WHERE {
?country a type:LandlockedCountries ;
rdfs:label ?country_name ;
prop:populationEstimate ?population .
}
The query looks for all land looked countries.
I don't understand why in the results there are not some countries which are classified on
"/dbpedia.org/class/yago/LandlockedCountries". For example, Paraguay (/dbpedia.org/page/ParaguAy) is classified but does not appear in the query result set. Can somebody explain me why?
Unfortunately, there are a small number of landlocked countries that do not have values for at least one of the country_name and populationEstimate properties. This is why they will not be returned in your query. If you run the following query, those countries will come up (those two attributes are set as OPTIONAL).
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX type: <http://dbpedia.org/class/yago/>
PREFIX prop: <http://dbpedia.org/property/>
SELECT ?country ?country_name ?population
WHERE {
?country a type:LandlockedCountries .
OPTIONAL {?country rdfs:label ?country_name Filter(lang(?country_name) = 'en')} .
OPTIONAL {?country prop:populationEstimate ?population} .
}
run query
For (slightly) better results, since some countries seem to be duplicated with erroneous capitalization (e.g. ParaguAy and Paraguay), the following query uses ?country dcterms:subject category:Landlocked_countries instead of the yago class.
run query