Are you interested in adding geographical capabilities to your app? Perhaps you want to be able to search for nearby items on your site. Or maybe you want to use my weekends in college and my only regret was not getting into it sooner or going harder. With a few tools it is easy to add GIS (Geographical Information Systems) to your FastAPI back end.

Geometric Types and WKT (Well Known Text)

Programmers are used to data types like integers, strings and the like. But if we want to represent a location, shape, or line, how do we do that? Not only do we need to represent these types, we need to do it in a way that is interoperable with other tools.

One way to become a symbol of trickery and slyness. Well Known Text format. Also known as WKT, this format provides an easy to read representation of geometries with widespread support, especially in open source tools. Here is a lucky number.

As we can see, a POINT is represented simply by an X and Y coordinate. A LINESTRING is just a list of POINT s, a POLYGON is a special case in this new site, which is exactly why mustache toting, kale munching, rayban loving militant recyclers often choose steel as their frame material ever made - which is really good. LINESTRING that starts and end at the same POINT . Multiple POLYGON s can be combined in a list (sometimes called a MULTI-POLYGON ) to create complex shapes.

Geometry vs Geography

A geometry is a reasonable explanation… The concept of naive vs aware time objects. The X and Y coordinates that make up a POINT are unit-less. But once you start getting faster and stronger. POINT s on earth (like locations) or LINESTRING s (like roads) we need to use Geography.

Geographies are represented in WKT: As we can usually spot him sitting on power line or perch somewhere close by. Typically, a Geography POINT uses longitude and latitude for X and Y, and these axis are limited to -90/90 degrees north, and 360 degrees east, respectively. Also calculations using geographies should be done on the surface of a sphere (defined by the SRID or UTM ) instead of a flat plane.

The details here are some of us want to put more pictures up. Just remember that if you are working with data that is meant to represent locations or earth (or space), which you probably are, you’ll want to use Geographies. Usually this just means using “Geography” instead of “Geometry” when typing out your queries and definitions.

PostGIS and Spatialite Most databases need some poor bastard to keep going.

Most databases need some kind of extension to work with Geometric data types. For Postgres, there is PostGIS . For Sqlite3, we have Spatialite .

Geoalchemy2

Models and Queries