I want to get a table to show the percentage of population in different countries.
For example,
Percentage
Country
30
USA
25
UK
I write and run codes below in https://dbpedia.org/sparql. When I run the code, I get a list of decimals in the attached picture.
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT (xsd:double(?population) / SUM(xsd:double(?population)) * 100)
WHERE {
?country dbo:populationTotal ?population .
}
GROUP BY ?population
Close to what I want to achieve but the respective countries' names are not shown. So I write a new code.
PREFIX xsd: <http://www.w3.org/2001/XMLSchema#>
SELECT (xsd:double(?population) / SUM(xsd:double(?population)) * 100) ?country
WHERE {
?country dbo:populationTotal ?population .
}
GROUP BY ?population
GROUP BY ?country
Then I got this error from the SPARQL Endpoint.
Virtuoso 37000 Error SP031: SPARQL compiler: Variable ?country is used in the result set outside aggregate and not mentioned in GROUP BY clause
Where did I do wrong? Please help me to point it out. I am eagerly to know my mistakes as this is my first time writing SPARQL queries (excitedd!)
P.s. Yes! I have been google-searching and stack-over searching when I got this error message. But I couldn't find one.
Related
I'm new to SPARQL and I'm a bit stuck on a part of an assignment I have. I'm querying dbpedia for all the countries in the European Union which have a total population >= 3000000. For each country I'd like to show their corresponding government type. I would like the final result set to contain 3 columns:
the English label for each country
the English label for each type of government
the total population value
and then sorted descending on the total population.
PREFIX dct: <http://purl.org/dc/terms/>
PREFIX dbo: <http://dbpedia.org/ontology/>
PREFIX dbp: <http://dbpedia.org/property/>
PREFIX dbrc: <http://dbpedia.org/resource/Category:>
SELECT DISTINCT ?country xsd:integer(?populationTotal) ?government_type ?engName ?gov_type
WHERE {
?country dct:subject dbrc:Member_states_of_the_European_Union ;
a dbo:Country ;
rdfs:label ?engName .
OPTIONAL { ?country dbo:governmentType ?government_type . ?government_type rdfs:label ?gov_type . }
OPTIONAL { ?country dbo:populationTotal ?populationTotal . }
FILTER (xsd:integer(?populationTotal) >= 3000000 && langMatches(lang(?engName), "en"))
FILTER (langMatches(lang(?gov_type), "en"))
} ORDER BY DESC(?populationTotal)
I've managed to get dbpedia to return all the info I need, however I'd like to only keep the columns above in bulletpoints and not the country column. I know there should be a way to return that country directly with the label however I'm having troubles getting any closer to a solution...
I have problem with SPARQL. I want to select something from category. For example subjects. I make query like this in http://dbpedia.org/snorql.
SELECT ?category ?subject WHERE
{
?category a skos:Concept .
?category skos:Concept: American_punk_rock_guitarists.
?category dct:subject ?subject .
} LIMIT 1000
I have error Virtuoso 37000. I don't understand why.
P.S. Is it good book for beginnier in SPARQL - Learning SPARQL, 2nd Edition
Querying and Updating with SPARQL 1.1 ?
You have at least one syntax error: the second colon (:) in the second triple.
Semantically... I don't really know the classes or predicates in dbpedia... but can skos:Concept be both a type and a predicate?
I wrote you a valid query that returns 10 members of the category "American_punk_rock_guitarists"
I put this together by going to dbpedia's faceted free text search and familiarizing myself with the concept of American punk rock guitarists, specifically Joey Ramone
prefix dbpcat: <http://dbpedia.org/resource/Category:>
SELECT ?subject ?category
WHERE
{ values ?category { dbpcat:American_punk_rock_guitarists } .
?subject dct:subject ?category }
LIMIT 10
I have been trying to do this query but im not sure about how is the syntax I need. I have seen a lot of examples of how to ask in a query to check if something is larger or shorter than other thing, but I have no idea of how to ask if something is IN other thing.
This is my last (failed) try:
PREFIX : <http:/dbpedia.org/resource/>
ASK
{
FILTER(<http:/dbpedia.org/resource/Paris> IN <http:/dbpedia.org/resource/Member_states_of_the_United_Nations>)
}
Part of the issue is that there's a DBpedia resource called
http:/dbpedia.org/resource/Member_states_of_the_United_Nations
but what you actually want, since its the value of the dct:subject property, is the category,
http://dbpedia.org/page/Category:Member_states_of_the_United_Nations
For instance, you can get a list of countries that are member states with a query like:
select ?country {
?country a dbo:Country ;
dct:subject dbc:Member_states_of_the_United_Nations
}
SPARQL results
However, Paris isn't a country that's a member. It's a city in France, which is a member. You can check whether something is a member with an ask query like:
ask {
dbr:France a dbo:Country ;
dct:subject dbc:Member_states_of_the_United_Nations
}
SPARQL results (true)
You could get a list of populated places in countries that are member with a query like:
select ?city ?country {
?city a dbo:PopulatedPlace ;
dbo:country ?country .
?country a dbo:Country ;
dct:subject dbc:Member_states_of_the_United_Nations .
}
SPARQL results (limited to 100)
and you can modify that to be an ask query that checks for cities with specific names. E.g.:
ask {
?city rdfs:label "Paris"#en ;
a dbo:PopulatedPlace ;
dbo:country ?country .
?country a dbo:Country ;
dct:subject dbc:Member_states_of_the_United_Nations .
}
SPARQL results (true)
Using the dc:hasPart term :
<http:/dbpedia.org/resource/Member_states_of_the_United_Nations> <http://dublincore.org/documents/dcmi-terms/#terms-hasPart> <http:/dbpedia.org/resource/Paris>
This is described in this w3 document.
Note: This question is different from SPARQL query to retrieve countries population from DBpedia. This question is about population density as understood by DBPedia itself.
How can I retrieve country population density from DBPedia?
I have tried the following, but Virtuoso endpoint returns an empty result set:
PREFIX p: <http://dbpedia.org/property/>
SELECT DISTINCT ?name ?populationDensity
WHERE {
?country a dbpedia-owl:Country .
?country rdfs:label ?name .
?country p:populationDensity ?populationDensity . }
Your current query returns an empty table because there is no ?country that fulfills your query that has the rdf:type dbpedia-owl:Country (represented by 'a'). Check that with this query.
To find the list of rdf:type's that the set of data that does use your populationDensity you could use this query. Following that lead you can just check all properties for Portugal and find that it does have populationDensity, but not the one you used.
This works:
PREFIX dbpedia-ont-PP: <http://dbpedia.org/ontology/PopulatedPlace/>
SELECT DISTINCT ?country ?populationDensity
WHERE {
?country a dbpedia-owl:Country .
?country dbpedia-ont-PP:populationDensity ?populationDensity .
}
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