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Latest revision as of 14:43, 10 July 2019

DBpedia Mappings Wiki

In this DBpedia Mappings Wiki you can help to enhance the information in DBpedia. The DBpedia Extraction Framework uses the mappings defined here to homogenize information extracted from Wikipedia before generating structured information in RDF.

Anybody can help by editing:

the DBpedia ontology schema (classes, properties, datatypes)
the DBpedia infobox-to-ontology mappings

Mappings can be written for a variety of languages, connecting multiligual information to a language-independent unified ontology schema (language-specific labels can be provided there).

Mapping Example

This is how you write a simple infobox mapping.

Mapping:Infobox_actor

{{TemplateMapping 
| mapToClass = Actor 
| mappings = 
   {{ PropertyMapping | templateProperty = name | ontologyProperty = foaf:name }}
   {{ PropertyMapping | templateProperty = birth_place | ontologyProperty = birthPlace }}
}}

This mapping extracts three information bits:

the type information (Actor)
the name of the actor
the actor's place of birth.

Therefore, three RDF triples for each Infobox_actor in the English Wikipedia are extracted. For example for Vince Vaughn

dbpedia:Vince_Vaughn  rdf:type                dbpedia-owl:Actor   .
dbpedia:Vince_Vaughn  foaf:name               "Vince Vaughn"@en   .
dbpedia:Vince_Vaughn  dbpedia-owl:birthPlace  dbpedia:Minneapolis .

Detailed Information

Check the Mapping Guide that defines the best practices for how to write clean, efficient mappings that extract lots of high-quality data
Take a look at the Mapping Statistics to search for relevant infoboxes to map.
How to edit the DBpedia ontology
How to edit infobox and table mappings
Use the DBpedia Extraction Framework to extract structured data

Prerequisites

If you would like to edit the mappings or ontology schema this is what you need:

a user account on this wiki (login/sign up)
editor rights: application for editor rights is done by:
- register for http://forum.dbpedia.org
- ask for editor rights here. Include your user name in the message and a short introduction of yourself.
a namespace for the language you want to write mappings for
- if the namespace does not exist already (see the left side bar) please request it at dbpedia-discussion@lists.sourceforge.net
If you will contribute frequently, get a Github account (see below)

Editorial Process

A significant quality problem until 2015 was that there was neither bug tracking nor discussion on the best approaches. A major strength of Wikipedia and Wikidata is that editors are in constant discussion and there are established editorial processes. Such were missing on this mapping wiki, and it is our collective task to rectify the situation. If you find a problem:

Post a new issue to one of the following trackers, depending on the nature of the issue:
- Mapping: https://github.com/dbpedia/mappings-tracker/issues
- Ontology: https://github.com/dbpedia/ontology-tracker/issues
- Extraction framework: https://github.com/dbpedia/extraction-framework/issues
Edit the corresponding Discussion page (of the mapping or ontology element):
- Describe the problem in detail. The reason to do it here and not in Github is so that we have most of the info in one place
- Provide a link to the issue
- Propose a solution if you'd like

Best Practices

If you write a best practice, list it here:

Focused investigations of massive problems that require discussion, fixes to many props/templates, documenting a pattern:

Testing Best Practices

Whenever we find or fix a problem, we should have some test cases for it. This serves many important purposes:

to illustrate the problem
as proof it works after the problem is fixed
to provide test cases for any bugs in the extraction framework (upstream bug reporting)

Every infobox mapping has a link "test this mapping", eg

http://mappings.dbpedia.org/server/mappings/fr/extractionSamples/Mapping_fr:Infobox_Ville_de_Serbie

Unfortunately this works mostly for EN dbpedia, see bug #289. But you can still test per resource, eg

This is even better because it provides specific test cases. Also provide a link to the corresponding wiki pages in edit mode, so the markup can be seen immediately. Add these to the mapping's Discussion page.

Eg on Mapping fr talk:Infobox Ville de Serbie we have:

Testing:
- page: https://fr.wikipedia.org/w/index.php?title=Požega_(Serbie)&action=edit
- result: http://mappings.dbpedia.org/server/extraction/fr/extract?title=Požega_(Serbie)&revid=&format=turtle-triples

We've asked the developers to add UTF-8 encoding #304, which will make it easier to inspect the output. Else you need to save it to file and open it in a proper editor.

Custom or Default Extractor

The above URLs use the default extractor, which extracts only labels and mappings. This is probably what you need for testing, since you're debugging the mapped triples, right? If you want to see more triples, add "&extractors=custom" to the URL. This runs all available extractors. But there is a limit in the extraction samples (1000 triples?) so for big articles this may not return all expected triples.

Let's illustrate with Elvis Presley: custom 921 triples, default 118 triples. So the limit is not reached in this case.

Copy IRIs not URL-encoded

The URLs above use non-ASCII characters, so they are International Resource Identifiers (IRIs). These are readable and allow a user to see what they represent. But when you copy from the browser's address box, an IRI is URL-encoded to an unreadable ugliness like:

The browsers do that for obscure historical reasons. Please be kind to your fellow editors and use an addon that preserves IRIs, eg:

Chrome addon: Copy URL

If you don't have such, you can use this trick:

Copy everything but the first letter "m"
Paste, then add the missing letter "m" (or "http://m").

Domain Validation

The Domain Validation service generates a list of domain exceptions, updating it daily. For more information please refer to A. Dimou, D. Kontokostas, M. Freudenberg, R. Verborgh, J. Lehmann, E. Mannens, S. Hellmann, and R. Van de Walle. Assessing and refining mappings to rdf to improve dataset quality. In Proceedings of the 14th International Semantic Web Conference, Oct. 2015.

For each predicate used in a mapping, it shows the expected domain class (defined for the predicate) and existing class (corresponding to that mapping). Please filter for your language (the first column) and correct as many errors as you can:

Make the existing class into a subclass of expected, OR
Correct (usually raise) the domain of predicate, OR
Correct the mapping to use the expected mapToClass

In all cases, document the property according to the changes you made! You can see some examples of such changes in this list of contributions

That's it!

That is all you need to kick-start. Your contributions will be available:

in the DBpedia Live end point shortly after your edit (currently only for English)
in the next DBpedia datasets release

Happy mapping!

About DBpedia

To learn more about DBpedia itself visit http://dbpedia.org/About.

@@ Line 1: / Line 1: @@
-== About DBpedia ==
+== DBpedia Mappings Wiki ==
+In this DBpedia Mappings Wiki you can help to enhance the information in DBpedia. The DBpedia Extraction Framework uses the mappings defined here to homogenize information extracted from Wikipedia before generating structured information in [http://en.wikipedia.org/wiki/Resource_Description_Framework RDF].
+Anybody can help by editing:
+* the [[How_to_edit_the_DBpedia_Ontology|DBpedia ontology schema]] (classes, properties, datatypes)
+* the [[How_to_edit_DBpedia_Mappings|DBpedia infobox-to-ontology mappings]]
+Mappings can be written for a variety of languages, connecting multiligual information to a language-independent unified ontology schema (language-specific labels can be provided [[How_to_edit_the_DBpedia_Ontology|there]]).
+== Mapping Example ==
+This is how you write a simple infobox mapping.
+'''Mapping:Infobox_actor'''
+<pre>
+{{TemplateMapping
+| mapToClass = Actor
+| mappings =
+   {{ PropertyMapping | templateProperty = name | ontologyProperty = foaf:name }}
+   {{ PropertyMapping | templateProperty = birth_place | ontologyProperty = birthPlace }}
+}}
+</pre>
+This mapping extracts three information bits:
+# the type information (Actor)
+# the name of the actor
+# the actor's place of birth.
+Therefore, three RDF triples for each Infobox_actor in the English Wikipedia are extracted. For example for [http://en.wikipedia.org/w/index.php?title=Vince_Vaughn&oldid=437756176 Vince Vaughn]
+<pre>
+dbpedia:Vince_Vaughn  rdf:type                dbpedia-owl:Actor   .
+dbpedia:Vince_Vaughn  foaf:name               "Vince Vaughn"@en   .
+dbpedia:Vince_Vaughn  dbpedia-owl:birthPlace  dbpedia:Minneapolis .
+</pre>
+== Detailed Information ==
+* Check the '''[[Mapping Guide]]''' that defines the best practices for how to write clean, efficient mappings that extract lots of high-quality data
+* Take a look at the '''[[Mapping_Statistics|Mapping Statistics]]''' to search for relevant infoboxes to map.
+* '''[[How_to_edit_the_DBpedia_Ontology|How to edit the DBpedia ontology]]'''
+* '''[[How_to_edit_DBpedia_Mappings|How to edit infobox and table mappings]]'''
+* [[Use the DBpedia Extraction Framework]] to extract structured data
+== Prerequisites ==
+If you would like to edit the mappings or ontology schema this is what you need:
+* a user account on this wiki (''[[Special:UserLogin|login/sign up]]'')
+* editor rights: application for editor rights is done by:
+** register for http://forum.dbpedia.org
+** ask for editor rights [https://forum.dbpedia.org/t/mappings-wiki-accounts/38 here]. Include your user name in the message and a short introduction of yourself.
+* a namespace for the language you want to write mappings for
+** if the namespace does not exist already (see the left side bar) please request it at [mailto:dbpedia-discussion@lists.sourceforge.net dbpedia-discussion@lists.sourceforge.net]
+* If you will contribute frequently, get a Github account (see below)
+== Editorial Process ==
+A significant quality problem until 2015 was that there was neither bug tracking nor discussion on the best approaches. A major strength of Wikipedia and Wikidata is that editors are in constant discussion and there are established editorial processes. Such were missing on this mapping wiki, and it is our collective task to rectify the situation. If you find a problem:
+* Post a new issue to one of the following trackers, depending on the nature of the issue:
+** Mapping: https://github.com/dbpedia/mappings-tracker/issues
+** Ontology: https://github.com/dbpedia/ontology-tracker/issues
+** Extraction framework: https://github.com/dbpedia/extraction-framework/issues
+* Edit the corresponding Discussion page (of the mapping or ontology element):
+** Describe the problem in detail. The reason to do it here and not in Github is so that we have most of the info in one place
+** Provide a link to the issue
+** Propose a solution if you'd like
+== Best Practices ==
+If you write a best practice, list it here:
+* [[Mapping Guide]] (thorough)
+* [http://vladimiralexiev.github.io/pres/20150209-dbpedia/add-mapping.html Adding a Mapping] (shorter)
+* [[Main Page#Editorial Process]]
+* [[Main Page#Testing Best Practices]]
+Focused investigations of massive problems that require discussion, fixes to many props/templates, documenting a pattern:
+* [[What's in a Name]]
+* [[Connecting Places]] [https://github.com/dbpedia/mappings-tracker/issues/29 #29]
+* [[Agent Relations]]
-[http://dbpedia.org/ DBpedia] is a community effort to extract structured information from Wikipedia and to make this information available on the Web. DBpedia allows you to ask sophisticated queries against Wikipedia, and to link other data sets on the Web to Wikipedia data. The [http://wiki.dbpedia.org/Datasets DBpedia knowledge base], which has been created by extracting stuctured information from Wikipedia, currently describes more than 2.9 million things, including at least 282,000 persons, 339,000 places (including 241,000 populated places), 88,000 music albums, 44,000 films, 15,000 video games, 119,000 organizations (including 20,000 companies and 29,000 educational institutions), 130,000 species and 4400 diseases.
+== Testing Best Practices ==
+Whenever we find or fix a problem, we should have some test cases for it. This serves many important purposes:
+* to illustrate the problem
+* as proof it works after the problem is fixed
+* to provide test cases for any bugs in the extraction framework (upstream bug reporting)
-== About this wiki  ==
+Every infobox mapping has a link "test this mapping", eg
+* http://mappings.dbpedia.org/server/mappings/fr/extractionSamples/Mapping_fr:Infobox_Ville_de_Serbie
-=== DBpedia Mappings ===
+Unfortunately this works mostly for EN dbpedia, see bug [https://github.com/dbpedia/extraction-framework/issues/289 #289]. But you can still test per resource, eg
+* http://mappings.dbpedia.org/server/extraction/fr/extract?title=Požega_(Serbie)&revid=&format=turtle-triples
+* http://mappings.dbpedia.org/server/extraction/bg/extract?title=Лили+Иванова&revid=&format=turtle-triples
-The type of Wikipedia content that is most valuable for the DBpedia extraction are infoboxes and tables. Infoboxes display an article's most relevant facts as a table of attribute-value pairs on the top right-hand side of the Wikipedia page.
+This is even better because it provides specific test cases.
+Also provide a link to the corresponding wiki pages in edit mode, so the markup can be seen immediately.
+Add these to the mapping's Discussion page.
-As Wikipedia's infobox template system has decentrally envolved over time, different communities of Wikipedia editors use different templates to describe the same type of things (e.g.
+Eg on [[Mapping fr talk:Infobox Ville de Serbie]] we have:
-infobox_city_japan, infobox_swiss_town and infobox_town_de). Different templates use different names for the same attribute (e.g. birthplace and
+* Testing:
-placeofbirth). As many Wikipedia editors do not strictly follow the recommendations given on the page that describes a template, attribute values are
+** page: https://fr.wikipedia.org/w/index.php?title=Požega_(Serbie)&action=edit
-expressed using a wide range of different formats and units of measurement.
+** result: http://mappings.dbpedia.org/server/extraction/fr/extract?title=Požega_(Serbie)&revid=&format=turtle-triples
-In order to overcome the problems of synonymous attribute names and multiple templates being used for the same type of things, the DBpedia project maps Wikipedia templates as well as tables within an article to the [http://wiki.dbpedia.org/Ontology DBpedia ontology].
+We've asked the developers to add UTF-8 encoding [https://github.com/dbpedia/extraction-framework/issues/304 #304], which will make it easier to inspect the output. Else you need to save it to file and open it in a proper editor.
-These mappings are specified using the DBpedia Mapping Language. The mapping language makes use of MediaWiki templates that define DBpedia ontology classes and properties as well as template/table to ontology mappings.
+=== Custom or Default Extractor ===
+The above URLs use the default extractor, which extracts only labels and mappings. This is probably what you need for testing, since you're debugging the mapped triples, right?
+If you want to see more triples, add "&extractors=custom" to the URL. This runs all available extractors.
+But there is a limit in the extraction samples (1000 triples?) so for big articles this may not return all expected triples.
-=== mappings.dpedia.org ===
+Let's illustrate with Elvis Presley: [http://mappings.dbpedia.org/server/extraction/en/extract?title=Elvis_Presley&revid=&format=turtle-triples&extractors=custom custom] 921 triples, [http://mappings.dbpedia.org/server/extraction/en/extract?title=Elvis_Presley&revid=&format=turtle-triples default] 118 triples.
+So the limit is not reached in this case.
-This wiki contains the infobox-to-ontology as well as the table-to-ontology mappings which are used by the DBpedia extraction framework. The framework collects the templates defined in this Wiki and extracts the Wikipedia content according to them (As of March 2010, only the dump extraction uses the mappings. DBpedia Live is going to follow shortly).
+=== Copy IRIs not URL-encoded ===
+The URLs above use non-ASCII characters, so they are '''International''' Resource Identifiers (IRIs).
+These are readable and allow a user to see what they represent.
+But when you copy from the browser's address box, an IRI is URL-encoded to an unreadable ugliness like:
+* http://mappings.dbpedia.org/server/extraction/fr/extract?title=Po%C5%BEega_(Serbie)&revid=&format=turtle-triples
+* http://mappings.dbpedia.org/server/extraction/bg/extract?title=%D0%9B%D0%B8%D0%BB%D0%B8+%D0%98%D0%B2%D0%B0%D0%BD%D0%BE%D0%B2%D0%B0&revid=&format=turtle-triples
-The pages below give an overview of all mappings:
+The browsers do that for obscure historical reasons.
+Please be kind to your fellow editors and use an addon that preserves IRIs, eg:
+* Chrome addon: [https://chrome.google.com/webstore/detail/copy-url/mkhnbhdofgaendegcgbmndipmijhbili Copy URL]
-* [http://mappings.dbpedia.org/index.php?title=Special%3AAllPages&from=&to=&namespace=102 Mappings]
+If you don't have such, you can use this trick:
-* [http://mappings.dbpedia.org/index.php?title=Special%3APrefixIndex&prefix=Table&namespace=102 Table Mappings]
+* Copy everything but the first letter "m"
-* [http://mappings.dbpedia.org/index.php?title=Special%3AAllPages&from=&to=&namespace=100 Ontology Classes]
+* Paste, then add the missing letter "m" (or "http://m").
-* [http://mappings.dbpedia.org/index.php?title=Special%3AAllPages&from=&to=&namespace=101 Ontology Properties]
+=== Domain Validation ===
+The [http://mappings.dbpedia.org/validation/index.html Domain Validation service] generates a list of domain exceptions, updating it daily.
+For more information please refer to A. Dimou, D. Kontokostas, M. Freudenberg, R. Verborgh, J. Lehmann, E. Mannens, S. Hellmann, and R. Van de Walle. [http://jens-lehmann.org/files/2015/iswc_rml_rdfunit.pdf Assessing and refining mappings to rdf to improve dataset quality]. In Proceedings of the 14th International Semantic Web Conference, Oct. 2015.
-The members of the DBpedia team are not able to extend the mappings to cover all Wikipedia infoboxes and tables, due to the size of the task and the knowledge required to map templates from exotic domains. Therefore, the idea of this Wiki is to enable the interested public to contribute to the definition of DBpedia mappings by updating existing mappings and by adding new mappings to this wiki.
+For each '''predicate''' used in a '''mapping''', it shows the '''expected''' domain class (defined for the predicate) and '''existing''' class (corresponding to that mapping).
+Please filter for your language (the first column) and correct as many errors as you can:
+* Make the '''existing''' class into a subclass of '''expected''', OR
+* Correct (usually raise) the domain of '''predicate''', OR
+* Correct the '''mapping''' to use the expected mapToClass
-''This wiki is read-only. If you like to edit the mappings or ontology schema, please [[Special:UserLogin|register]] and the DBpedia team will add you to the editors list.''
+In all cases, ''document'' the property according to the changes you made! You can see some examples of such changes in this [http://mappings.dbpedia.org/index.php?limit=50&tagfilter=&title=Special%3AContributions&contribs=user&target=VladimirAlexiev&namespace=&year=2015&month=8 list of contributions]
-== Tutorials ==
+== That's it! ==
+That is all you need to kick-start. Your contributions will be available:
+* in the [http://live.dbpedia.org/ DBpedia Live] end point shortly after your edit (currently only for English)
+* in the next [http://dbpedia.org/downloads DBpedia datasets] release
-The '''Specification of the DBpedia Mapping Language''' can be found [http://dbpedia.svn.sourceforge.net/viewvc/dbpedia/trunk/extraction/doc/mapping%20language/DBpedia%20Mapping%20Language.pdf here]. Please find below step-by-step tutorials on:
+''Happy mapping!''
-* [[Ontology_Editing|How to edit the ontology schema]]
+== About DBpedia ==
-* How to write a mapping
+To learn more about DBpedia itself visit http://dbpedia.org/About.
-** [[Writing_Mappings/Templates|Template mappings]]
-** [[Writing_Mappings/Tables|Table mappings]]

Main Page: Difference between revisions

Latest revision as of 14:43, 10 July 2019

Contents

DBpedia Mappings Wiki

Mapping Example

Detailed Information

Prerequisites

Editorial Process

Best Practices

Testing Best Practices

Custom or Default Extractor

Copy IRIs not URL-encoded

Domain Validation

That's it!

About DBpedia

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