Say I need to fetch content from wikipedia about all mountains. My target is to show initial paragraph, and an image from respective article (eg. Monte Rosa and Vincent Pyramid.
I came to know about dbpedia, and with some research got to find that it provides live queries into wiki database directly.
I have 2 questions:
1 - I am finding it difficult how could I formulate my queries. I can't play around iSPARQL. I tried following query but it throws error saying invalid xml.
SELECT DISTINCT ?Mountain FROM <http://dbpedia.org> WHERE {
[] rdf:type ?Mountain
}
2 - My requirement is to show only mountains that have at least 1 image (I need to show this image too). Now the ones I listed above have images, but how could I be sure? Also, looking at both examples I see many fields differ in wiki articles - so for future extension it maybe quite difficult to fetch them.
I just want to reject those which do not have sufficient data or description.
How can I filter out mountains based on pictures present?
UPDATE:
My corrected query, which solves my first problem:
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
SELECT DISTINCT ?name ?description
WHERE {
?name rdf:type <http://dbpedia.org/ontology/Mountain>;
dbpedia-owl:abstract ?description .
}
You can also query dbpedia using its SPARQL endpoint (less fancy than iSPARQL). To find out more about what queries to write, take a look at the DBpedia's datasets page. The examples there show how one can select pages based on Wikipedia categories. To select resources in the Wikipedia Mountains category, you can use the following query:
select ?mountain where {
?mountain a dbpedia-owl:Mountain .
}
SPARQL Results
Once you have some of these links in hand, you can look at them in a web browser and see the data associated with them. For instance the page for Mount Everest shows lots of properties. For restricting results to those pages that have an image, you might be interested in the dbpedia-owl:thumbnail property, or perhaps better yet foaf:depiction. For the introductory paragraph, you probably want something like the dbpedia-owl:abstract. Using those, we can enhance the query from before. The following query finds things in the category Stratovolcanoes with an abstract and an depiction. Since StackOverflow is an English language site, I've restricted the abstracts to those in English.
select * where {
?mountain a dbpedia-owl:Mountain ;
dbpedia-owl:abstract ?abstract ;
foaf:depiction ?depiction .
FILTER(langMatches(lang(?abstract),"EN"))
}
LIMIT 10
SPARQL Results
Related
I am new to SPARQL and trying to fetch a movie adapted from specific book from dbpedia. This is what I have so far:
PREFIX onto: <http://dbpedia.org/ontology/>
SELECT *
WHERE
{
<http://dbpedia.org/page/2001:_A_Space_Odyssey> a ?type.
?type onto:basedOn ?book .
?book a onto:Book
}
I can't get any results. How can I do that?
When using any web resource, and in your case the property :basedOn, you need to make sure that you have declared the right prefix. If you are querying from the DBpedia SPARQL endpoint, then you can directly use dbo:basedOneven without declaring it, as it is among predefined. Alternatively, if you want to use your own, or if you are using another SPARQL client, make sure that whatever short name you choose for this property, you declare the prefix for http://dbpedia.org/ontology/.
Then, first, to get more result you may not restrict the type of the subject of this triple pattern, as there could be movies that actually not type as such. So, a query like this
select distinct *
{
?movie dbo:basedOn ?book .
?book a dbo:Book .
}
will give you lots of good results but not all. For example, the resource from your example will be missing. You can easily check test the available properties between these two resource with a query like this:
select ?p
{
{<http://dbpedia.org/resource/2001:_A_Space_Odyssey_(film)> ?p <http://dbpedia.org/resource/2001:_A_Space_Odyssey> }
UNION
{ <http://dbpedia.org/resource/2001:_A_Space_Odyssey> ?p <http://dbpedia.org/resource/2001:_A_Space_Odyssey_(film)>}
}
You'll get only one result:
http://www.w3.org/2000/01/rdf-schema#seeAlso
(note that the URI is with 'resource', not with 'page')
Then you may search for any path between the two resource, using the method described here, or find a combination of other patterns that would increase the number of results.
Hi I'm trying to learn how to query DBpedia using SPARQL. I can't find any website/source that shows me how do this and I'm finding it difficult to learn how to use all the properties (like the ones available at http://mappings.dbpedia.org/index.php?title=Special%3AAllPages&from=&to=&namespace=202 ). Any good source I can learn from?
So for example if I want to check if the wikipedia page http://en.wikipedia.org/wiki/Inception is a movie (property film) or not, how do I do that?
The wikipedia URL http://en.wikipedia.org/wiki/Inception maps to the dbpedia URI http://dbpedia.org/resource/Inception. Dbpedia has a SPARQL endpoint at: http://dbpedia.org/sparql, which you may use to run queries either programmatically or via the html interface.
To check if http://dbpedia.org/page/Inception is a "movie", you have many options. To give you an idea:
If you know the URI of "movie" in dbpedia (it is http://schema.org/Movie), then run an ASK query to check against that type. ASK will return true/false based on whether the pattern in the where clause is valid against the data:
ASK where {
<http://dbpedia.org/resource/Inception> a <http://schema.org/Movie>
}
If you don't know the URI of "movie" then you have a number of options. For example:
Execute an ASK query with a filter on whether the resource has a type that contains the word "movie" somewhere in its uri (or its associated rdfs:label, or both). You would use a regular expression for this:
ASK where {
<http://dbpedia.org/resource/Inception> a ?type .
FILTER regex(str(?type), "^.*movie", "i")
}
Same idea, but return all matches and post-process the results (programmatically I pressume) to see if they match your request:
select distinct ?type where {
<http://dbpedia.org/resource/Inception> a ?type .
FILTER regex(str(?type), "^.*movie", "i")
}
Return all the types of the resource without applying a filter and post-process to see if they match your request:
select distinct ?type where {
<http://dbpedia.org/resource/Inception> a ?type
}
Many options. The SPARQL spec is you number one resource.
First I suggest you start reading up on what exactly SPARQL is. There are tons of really good tutorials such as: this.
If you want to write SPARQL queries on dbpedia, there are various endpoints that you can use. They don't always accept all features that are supported by SPARQL, but if you don't want to go through the trouble of installing one locally, they can be a relatively reliable test environment. The queries that I am going to write below, have been tested on Virtuoso endpoint.
Let's say you want to find all the movies in dbpedia. You first need to know what is the URI for a movie type in dbpedia. If you open Inception in dbpedia, you can see that the type dbpedia-owl:Film is associated to it. So if you want to get the first 100 movies, you just need to call:
select distinct *
where {
?s ?o dbpedia-owl:Film
} LIMIT 100
If you want o know more about each of these movies, you just need to expand your queries by expanding the triples.
select distinct *
where {
?s ?p dbpedia-owl:Film.
?s ?x ?y.
} LIMIT 100
I am struggling with the following SPARQL query executed via at DBpedia's SPARQL endpoint:
select (count(?abstract) as ?count)
where {
<http://dbpedia.org/resource/Linked_Data> dbpedia-owl:abstract ?abstract .
}
SPARQL seems pretty simple and when I look at the linked data page, it appears that expected result would be 9. But the actual response is 0. Is my understanding or expectation wrong? Could someone more experienced clarify please?
There are nine abstracts on the linked data article, but the title of the article is "Linked data", not "Linked Data", and the capitalization matters. Thus, you can do this, and see all nine abstracts getting counted:
select (count(?abstract) as ?nAbstract) {
dbpedia:Linked_data dbpedia-owl:abstract ?abstract
}
SPARQL results
The public endpoint defines the dbpedia: prefix. It's short for http://dbpedia.org/resource, so dbpedia:Linked_data is just short for http://dbpedia.org/resource/Linked_data. That's the URI for the resource, but when you put it into a web browser, you'll get redirected to a human readable HTML version at http://dbpedia.org/page/Linked_data.
I have a direct link to a DBPedia page (e.g. Argentina) and I'd like to retrieve some or all links with the owl:sameAs label (e.g. wikidata, freebase, etc.)
All the tutorials that I've read focus on retrieving group of object with particular features (e.g., French films).
I've also read this but it just returns one result instead of the entire list of owl:sameAs.
How do I do this?
The following query returns what you're looking for:
PREFIX dbpedia: <http://dbpedia.org/resource/>
SELECT ?obj WHERE {
dbpedia:Argentina (owl:sameAs|^owl:sameAs) ?obj
}
Note that the URI of the resource is actually http://dbpedia.org/resource/Argentina, not page/Argentina. When you put the first URI into a web browser, though, you get redirected to the latter. Be sure to use the former in your query (or just use the prefix dbpedia:).
I'm trying to make a SPARQL query using Prolog and DBpedia. My objective is to tag in text all Persons, so for retrieving famous people I made this query that remove all results like Music groups(Band) and Organization, since I want to tag only real people and not abstract
select ?person where{
{
?person a dbpedia-owl:Person; rdfs:label "Name Surname" #it.
}
UNION
{
?person a dbpedia-owl:Person; foaf:name "Name"#it; foaf:surname "Surname"#it.
}
UNION
{
?person a dbpedia-owl:Person; foaf:name "Name Surname"#it.
}
FILTER NOT EXISTS {
{ ?subject <http://airpedia.org/ontology/type_with_conf#10> dbpedia-owl:Band .
?subject rdfs:label ?artistName .
FILTER ( str(?artistName) = "Name Surname" )
}
UNION
{
?subject <http://airpedia.org/ontology/type_with_conf#10> dbpedia-owl:Organisation .
?subject rdfs:label ?artistName .
FILTER ( str(?artistName) = "Name Surname" )
}
}
}
I use It. version of Dbpedia if you run this query use this version although the results will not be good for me.
So for example if I search "Metallica" as a person i don't want to get results cause is it a Band or(for me, but in this case is Metallica are an Organisation too) an Organisation
and it works good this are the results Metallica Query Results and those are for "Michael Jackson" Michael Jackson Query results
My problem is when i put someone that is not a Singer or a Music band for example if i try something like "Jim Carrey" i get " error transction timed out Jim Carrey.
I think I got this problem because those properties are Undefined for Jim Carrey, but i tried an to put an OPTIONAL marker in each subquery in the first filter, but i get too the same error
I put the code in a pastebin file so you can find all three query
I know that i should not use Static String in a query or there are a lot of better mode but i need that since i compose the query with prolog and than send to sparql online so i must do in this way.
TO #Joshua I tried to remove the FILTER(String) in the NOT EXIST (Filter) But I will not work anymore thanks however for helping me
Excuse me for too much editing but i resolved some part of the starting problem but didn't find a solution
First problem :Filtering results based on specific properties with specific values. (Works)
Second : The first works only for Things with that specific property (as show above) like(Metallica,Michael Jackson, The Beatles, ...) but not for thos without the properties in the filter.
(i can't use more than two link because I'm a newbe so i will put a link in the comments with a pastebin links with the 3 Query and the results of they)