https://github.com/bosth/plpygis

PL/Python for PostGIS
https://github.com/bosth/plpygis

geospatial plpython postgresql

Last synced: 29 days ago
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PL/Python for PostGIS

• Host: GitHub
• URL: https://github.com/bosth/plpygis
• Owner: bosth
• License: gpl-3.0
• Created: 2017-07-31T05:28:15.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2024-04-30T06:20:55.000Z (6 months ago)
• Last Synced: 2024-05-30T01:06:00.226Z (5 months ago)
• Topics: geospatial, plpython, postgresql
• Language: Python
• Homepage: https://vimeo.com/248099711
• Size: 137 KB
• Stars: 20
• Watchers: 4
• Forks: 3
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

        
# plpygis

`plpygis` is a pure Python module with no dependencies that can convert geometries between [Well-known binary](https://en.wikipedia.org/wiki/Well-known_binary) (WKB/EWKB), [Well-known Text](https://en.wikipedia.org/wiki/Well-known_text_representation_of_geometry) (WKT/EWKT) and GeoJSON representations. `plpygis` is mainly intended for use in PostgreSQL [PL/Python](https://www.postgresql.org/docs/current/plpython.html) functions to augment [PostGIS](https://postgis.net/)'s native capabilities.

## Basic usage

`plpygis` implements several subclasses of the `Geometry` class, such as `Point`, `LineString`, `MultiPolygon` and so on:

```python

>>> from plpygis import Point

>>> p = Point((-124.005, 49.005), srid=4326)

>>> print(p.ewkb)

0101000020e6100000b81e85eb51005fc0713d0ad7a3804840

>>> print(p.geojson)

{'type': 'Point', 'coordinates': [-124.005, 49.005]}

>>> p.z = 1

>>> print(p.wkt)

POINT Z (-124.005 49.005 1)

```

## Usage with PostGIS

`plpygis` is designed to provide an easy way to implement PL/Python functions that accept `geometry` arguments or return `geometry` results. The following example will take a PostGIS `geometry(Point)` and use an external service to create a `geometry(PointZ)`.

```pgsql

CREATE OR REPLACE FUNCTION add_elevation(geom geometry(POINT))

  RETURNS geometry(POINTZ)

AS $$

  from plpygis import Geometry

  from requests import get

  p = Geometry(geom)

  response = get(f'https://api.open-meteo.com/v1/elevation?longitude={p.x}&latitude={p.y}')

  if response.status_code == 200:

      content = response.json()

      p.z = content['elevation'][0]

      return p

  else:

      return None

$$ LANGUAGE plpython3u;

```

The `Geometry()` constructor will convert a PostGIS `geometry` that has been passed as a parameter to the PL/Python function into one of its `plpygis` subclasses. A `Geometry` that is returned from the PL/Python function will automatically be converted back to a PostGIS `geometry`.

The function above can be called as part of an SQL query:

```pgsql

SELECT

    name,

    add_elevation(geom)

FROM

    city;

```

## Documentation

Full `plpygis` documentation is available at .

[![Continuous Integration](https://github.com/bosth/plpygis/workflows/tests/badge.svg)](https://github.com/bosth/plpygis/actions?query=workflow%3A%22tests%22) [![Documentation Status](https://readthedocs.org/projects/plpygis/badge/?version=latest)](http://plpygis.readthedocs.io/en/latest/?badge=latest)