Wikidata
In their own words,
Wikidata is a free, collaborative, multilingual, secondary knowledge base, collecting structured data to provide support for Wikipedia, Wikimedia Commons, the other wikis of the Wikimedia movement, and anyone in the world.
Wikidata consists of items each one having a label, a description and any number of aliases.
Statements describe detailed characteristics of an Item and consist of a property and a value.
| Item | Property | Value |
|---|---|---|
| Q42 | P69 | Q691283 |
| Douglas Adams | educated at | St John's College |
For a person, you can add a property to specify where they were educated, by specifying a value for a school. For buildings, you can assign geographic coordinates properties by specifying longitude and latitude values. Properties can also link to external databases. A property that links an item to an external database, such as an authority control database used by libraries and archives, is called an identifier.
Item: In Wikidata, items are used to represent all the things in human knowledge, including topics, concepts, and objects. For example, the "1988 Summer Olympics", "love", "Elvis Presley", and "gorilla" are all items in Wikidata.
Label: The label is the most common name that the item would be known by. It does not need to be unique, in that multiple items can have the same label, however no two items may have both the same label and the same description.
Description: The description on a Wikidata entry is a short phrase designed to disambiguate items with the same or similar labels. A description does not need to be unique; multiple items can have the same description, however no two items can have both the same label and the same description.
Alias: Aliases are alternative names for items that are placed in the Also known as column of the table on top of every Wikidata item page.
There are a number of ways to access Wikidata using built-in tools, external tools, or programming interfaces.
- Wikidata Query looks like a potential tool to explore Wikidata items. The tools page has an extensive list of interesting projects to explore.
- One can (retrieve all data programmatically) use different APIs and service.
SELECT ?countryLabel ?capitalLabel WHERE { ?country wdt:P31 wd:Q6256; # Instance of country wdt:P30 wd:Q46. # Located in the continent of Europe ?country wdt:P36 ?capital. # Has capital SERVICE wikibase:label { bd:serviceParam wikibase:language "en". } } LIMIT 10
| countryLabel | capitalLabel |
|---|---|
| Kosovo | Prishtina |
| Galicia | Santiago de Compostela |
| Catalonia | Barcelona |
| Kingdom of Iberia | Tbilisi |
| Kingdom of Iberia | Armazi |
| Kingdom of the Netherlands | Amsterdam |
| Kingdom of Denmark | Copenhagen |
| Norway | Oslo |
| England | London |
| Scotland | Edinburgh |
SELECT ?countryLabel ?capitalLabel ?population WHERE { ?country wdt:P31 wd:Q6256; # Instance of country wdt:P36 ?capital. # Has capital ?capital wdt:P1082 ?population. # Population SERVICE wikibase:label { bd:serviceParam wikibase:language "en". } } ORDER BY DESC(?population) LIMIT 10
| countryLabel | capitalLabel | population |
|---|---|---|
| People's Republic of China | Beijing | 21893095 |
| Bangladesh | Dhaka | 16800000 |
| Japan | Tokyo | 14264798 |
| Russia | Moscow | 12455682 |
| Democratic Republic of the Congo | Kinshasa | 11855000 |
| Indonesia | Jakarta | 10562088 |
| Peru | Lima | 9943800 |
| South Korea | Seoul | 9668465 |
| Egypt | Cairo | 9606916 |
| Mexico | Mexico City | 9209944 |