By Jack Dougherty, last updated December 21, 2016
TO DO insert sample map iframe
Leaflet, a friendly and flexible open-source code library for creating interactive web maps, plays nicely with Socrata, an open data platform used by several government agencies and organizations. Benefits of pairing Leaflet and Socrata:
- Although the Socrata data platform includes built-in visualization tools for anyone to create charts and maps, Leaflet gives you more control over your map design. Furthermore, Leaflet allows you to create maps that bring together data from both Socrata and non-Socrata sources.
- Socrata datasets include an API (application program interface) endpoint, in the form of a web address. This endpoint enables other computers to easily access the most recent data online, instead of a static version that was manually downloaded.
Newer Socrata datasets that include locations (such as latitude and longitude coordinates) also provide endpoints in GeoJSON format. Since Leaflet maps easily process GeoJSON data, only a few lines of code are required.
However, Socrata GeoJSON endpoints do not currently support "real-time" data, such as up-to-the-minute locations of public transportation, etc. In these cases, you may need to access data through a provider other than Socrata, most likely in a different format, which may require more coding skills.
TODO clean up my rough notes and add visuals
Go to any Socrata open data platform, find a dataset, and click the API tab
Copy the API endpoint. The default version ends in .json
If you're new to APIs, test the endpoint by pasting it into your browser (Chrome works best at this), and you will see its data stream in JSON format.
Test if this Socrata endpoint supports GeoJSON format by changing the suffix in your browser from
.geojson. GeoJSON format works best with Leaflet because the coding is simpler.
If your endpoint supports GeoJSON format, your browser will display a data stream similar to the one below:
add sample GeoJSON stream
Or if you receive the following error, you probably are viewing an older Socrata endpoint that does not support GeoJSON format, but only JSON format:
GeoJSON/SoQLPack MimeType is only supported for new backend views
If your Socrata endpoint only supports JSON format, but includes data columns with latitude and longitude, see other Leaflet examples further below.
- Socrata requires developers to register for a free app token at https://dev.socrata.com/register
- map https://jackdougherty.github.io/leaflet-socrata/index.html
- code https://github.com/jackdoughety/leaflet-socrata/index.html
- data https://data.hartford.gov/Public-Health/Current-Class-1-Class-4-Food-Establishments/xkvv-76v8
note: location data appears as latitude and longitude coordinates in the
steps to create your own (MORE TODO HERE)
select API button, copy endpoint, and change suffix from .json to .geojson
copy this Leaflet map template, which includes this key section of code:
paste and explain the code
- map https://jackdougherty.github.io/leaflet-socrata/index-geojson-filter-circle.html
- code https://github.com/jackdoughety/leaflet-socrata/
- data https://data.ct.gov/Environment-and-Natural-Resources/Agricultural-Commoditites-Grown-By-Farmer/y6p2-px98
- map https://jackdougherty.github.io/leaflet-socrata/index-control-layers.html
- code https://github.com/jackdoughety/leaflet-socrata/index-control-layers.html
- map https://jackdougherty.github.io/leaflet-socrata/index-json.html
- code https://github.com/jackdoughety/leaflet-socrata/index-json.html
- data https://opendata.demo.socrata.com/Government/Kentucky-Farmers-Market-Map/3bfj-rqn7
Improve this book: Donate to DataViz students and add comments or revisions.