I am happy to report that an initial, yet fully functional RDF export for Wikidata is now available. The exports can be created using the wda-export-data.py script of the wda toolkit [1]. This script downloads recent Wikidata database dumps and processes them to create RDF/Turtle files. Various options are available to customize the output (e.g., to export statements but not references, or to export only texts in English and Wolof). The file creation takes a few (about three) hours on my machine depending on what exactly is exported.

For your convenience, I have created some example exports based on yesterday's dumps. These can be found at [2]. There are three Turtle files: site links only, labels/descriptions/aliases only, statements only. The fourth file is a preliminary version of the Wikibase ontology that is used in the exports.

The export format is based on our earlier proposal [3], but it adds a lot of details that had not been specified there yet (namespaces, references, ID generation, compound datavalue encoding, etc.). Details might still change, of course. We might provide regular dumps at another location once the format is stable.

As a side effect of these activities, the wda toolkit [1] is also getting more convenient to use. Creating code for exporting the data into other formats is quite easy.

Features and known limitations of the wda RDF export:

(1) All current Wikidata datatypes are supported. Commons-media data is correctly exported as URLs (not as strings).

(2) One-pass processing. Dumps are processed only once, even though this means that we may not know the types of all properties when we first need them: the script queries wikidata.org to find missing information. This is only relevant when exporting statements.

(3) Limited language support. The script uses Wikidata's internal language codes for string literals in RDF. In some cases, this might not be correct. It would be great if somebody could create a mapping from Wikidata language codes to BCP47 language codes (let me know if you think you can do this, and I'll tell you where to put it)

(4) Limited site language support. To specify the language of linked wiki sites, the script extracts a language code from the URL of the site. Again, this might not be correct in all cases, and it would be great if somebody had a proper mapping from Wikipedias/Wikivoyages to language codes.

(5) Some data excluded. Data that cannot currently be edited is not exported, even if it is found in the dumps. Examples include statement ranks and timezones for time datavalues. I also currently exclude labels and descriptions for simple English, formal German, and informal Dutch, since these would pollute the label space for English, German, and Dutch without adding much benefit (other than possibly for simple English descriptions, I cannot see any case where these languages should ever have different Wikidata texts at all).

Feedback is welcome.



[1] https://github.com/mkroetzsch/wda
    Run "python wda-export.data.py --help" for usage instructions
[2] http://semanticweb.org/RDF/Wikidata/
[3] http://meta.wikimedia.org/wiki/Wikidata/Development/RDF

Markus Kroetzsch, Departmental Lecturer
Department of Computer Science, University of Oxford
Room 306, Parks Road, OX1 3QD Oxford, United Kingdom
+44 (0)1865 283529               http://korrekt.org/

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