WikidataQueryServiceR
================

  - [Installation](#installation)
  - [Usage](#usage)
      - [Example: fetching genres of a particular
        movie](#example-fetching-genres-of-a-particular-movie)
      - [Fetching queries from Wikidata’s examples
        page](#fetching-queries-from-wikidatas-examples-page)
  - [Links for learning SPARQL](#links-for-learning-sparql)
  - [Additional Information](#additional-information)

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This is an R wrapper for the [Wikidata Query Service
(WDQS)](https://www.mediawiki.org/wiki/Wikidata_query_service) which
provides a way for tools to query
[Wikidata](https://www.wikidata.org/wiki/Wikidata:Main_Page) via
[SPARQL](https://en.wikipedia.org/wiki/SPARQL) (see the beta at
<https://query.wikidata.org/>). It is written in and for R, and was
inspired by Os Keyes’
[WikipediR](https://github.com/Ironholds/WikipediR) and
[WikidataR](https://github.com/Ironholds/WikidataR) packages.

**Author:** Mikhail Popov (Wikimedia Foundation)
 **License:**
[MIT](http://opensource.org/licenses/MIT)
 **Status:** Active

## Installation

``` r
install.packages("WikidataQueryServiceR")
```

To install the development version:

``` r
# install.packages("remotes")
remotes::install_github("bearloga/WikidataQueryServiceR")
```

## Usage

``` r
library(WikidataQueryServiceR)
```

    ## See ?WDQS for resources on Wikidata Query Service and SPARQL

You submit SPARQL queries using the `query_wikidata()` function.

### Example: fetching genres of a particular movie

In this example, we find an “instance of”
([P31](https://www.wikidata.org/wiki/Property:P31)) “film”
([Q11424](https://www.wikidata.org/wiki/Q11424)) that has the label “The
Cabin in the Woods” ([Q45394](https://www.wikidata.org/wiki/Q45394)),
get its genres ([P136](https://www.wikidata.org/wiki/Property:P136)),
and then use [WDQS label
service](https://www.mediawiki.org/wiki/Wikidata_query_service/User_Manual#Label_service)
to return the genre labels.

``` r
query_wikidata('SELECT DISTINCT
  ?genre ?genreLabel
WHERE {
  ?film wdt:P31 wd:Q11424.
  ?film rdfs:label "The Cabin in the Woods"@en.
  ?film wdt:P136 ?genre.
  SERVICE wikibase:label { bd:serviceParam wikibase:language "en". }
}')
```

| genre                                     | genreLabel           |
| :---------------------------------------- | :------------------- |
| <http://www.wikidata.org/entity/Q3072049> | zombie film          |
| <http://www.wikidata.org/entity/Q471839>  | science fiction film |
| <http://www.wikidata.org/entity/Q859369>  | comedy-drama         |
| <http://www.wikidata.org/entity/Q1342372> | monster film         |
| <http://www.wikidata.org/entity/Q853630>  | slasher film         |
| <http://www.wikidata.org/entity/Q224700>  | comedy horror        |

For more example SPARQL queries, see [this
page](https://www.wikidata.org/wiki/Wikidata:SPARQL_query_service/queries/examples)
on [Wikidata](https://www.wikidata.org/wiki/Wikidata:Main_Page).

`query_wikidata()` can accept multiple queries, returning a (potentially
named) list of data frames. If the vector of SPARQL queries is named,
the results will inherit those names.

### Fetching queries from Wikidata’s examples page

The package provides a
[WikipediR](https://github.com/Ironholds/WikipediR/)-based function for
getting SPARQL queries from the [WDQS examples
page](https://www.wikidata.org/wiki/Wikidata:SPARQL_query_service/queries/examples).

``` r
sparql_query <- get_example(c("Cats", "How many states this US state borders"))
```

``` r
sparql_query[["How many states this US state borders"]]
```

``` sparql
 #added before 2016-10
SELECT ?state ?stateLabel ?borders
WHERE
{
  {
    SELECT ?state (COUNT(?otherState) as ?borders)
    WHERE
    {
    ?state wdt:P31 wd:Q35657 .
    ?otherState wdt:P47 ?state .
    ?otherState wdt:P31 wd:Q35657 .
    }
    GROUP BY ?state
  }
  SERVICE wikibase:label {
    bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en" .
  }
}        
ORDER BY DESC(?borders) 
```

Now we can run all extracted SPARQL queries:

``` r
results <- query_wikidata(sparql_query)
lapply(results, dim)
```

    ## $Cats
    ## [1] 147   2
    ## 
    ## $`How many states this US state borders`
    ## [1] 48  3

``` r
head(results$`How many states this US state borders`)
```

| state                                  | stateLabel   | borders |
| :------------------------------------- | :----------- | ------: |
| <http://www.wikidata.org/entity/Q1509> | Tennessee    |       8 |
| <http://www.wikidata.org/entity/Q1581> | Missouri     |       8 |
| <http://www.wikidata.org/entity/Q1261> | Colorado     |       7 |
| <http://www.wikidata.org/entity/Q1603> | Kentucky     |       7 |
| <http://www.wikidata.org/entity/Q1400> | Pennsylvania |       6 |
| <http://www.wikidata.org/entity/Q1211> | South Dakota |       6 |

## Links for learning SPARQL

  - [A beginner-friendly course for
    SPARQL](https://www.wikidata.org/wiki/Wikidata:A_beginner-friendly_course_for_SPARQL)
  - Building a SPARQL query: [Museums on
    Instagram](https://www.wikidata.org/wiki/Help:SPARQL/Building_a_query/Museums_on_Instagram)
  - [SPARQL Query
    Examples](https://www.wikidata.org/wiki/Wikidata:SPARQL_query_service/queries/examples)
    for WDQS
  - [Using SPARQL to access Linked Open
    Data](http://programminghistorian.org/lessons/graph-databases-and-SPARQL)
    by Matthew Lincoln
  - Interesting or illustrative [SPARQL
    queries](https://www.wikidata.org/wiki/Wikidata:SPARQL_query_service/queries)
    for Wikidata
  - Wikidata [2016 SPARQL
    Workshop](https://www.wikidata.org/wiki/Wikidata:SPARQL_query_service/2016_SPARQL_Workshop)
  - [Wikidata SPARQL Query video
    tutorial](https://www.youtube.com/watch?v=1jHoUkj_mKw) by Navino
    Evans
  - *[Learning SPARQL](http://www.learningsparql.com/)* by Bob DuCharme
  - [WDQS User
    Manual](https://www.mediawiki.org/wiki/Wikidata_query_service/User_Manual)

## Additional Information

Please note that this project is released with a [Contributor Code of
Conduct](https://github.com/bearloga/WikidataQueryServiceR/blob/master/CONDUCT.md).
By participating in this project you agree to abide by its terms.
