Skip to main content

A Python library for enforcing polygon ring winding order in GeoJSON

Project description

geojson-rewind

Run tests codecov PyPI Version License Python Compatibility Code style: black

A Python library for enforcing polygon ring winding order in GeoJSON

The GeoJSON spec mandates the right hand rule:

A linear ring MUST follow the right-hand rule with respect to the area it bounds, i.e., exterior rings are counterclockwise, and holes are clockwise.

This helps you generate compliant Polygon and MultiPolygon geometries.

Note: Co-ordinates in the input data are assumed to be WGS84 with (lon, lat) ordering, as per RFC 7946. Input with co-ordinates using any other CRS may lead to unexpected results.

Installation

pip install geojson-rewind

Usage

As a Library

Enforce RFC 7946 ring winding order (input/output is a GeoJSON string):

>>> from geojson_rewind import rewind

>>> input = """{
...      "geometry": {   "coordinates": [   [   [100, 0],
...                                             [100, 1],
...                                             [101, 1],
...                                             [101, 0],
...                                             [100, 0]]],
...                      "type": "Polygon"},
...      "properties": {"foo": "bar"},
...      "type": "Feature"}"""

>>> output = rewind(input)

>>> output
'{"geometry": {"coordinates": [[[100, 0], [101, 0], [101, 1], [100, 1], [100, 0]]], "type": "Polygon"}, "properties": {"foo": "bar"}, "type": "Feature"}'

>>> type(output)
<class 'str'>

Enforce RFC 7946 ring winding order (input/output is a python dict):

>>> from geojson_rewind import rewind

>>> input = {
...     'geometry': {   'coordinates': [   [   [100, 0],
...                                            [100, 1],
...                                            [101, 1],
...                                            [101, 0],
...                                            [100, 0]]],
...                     'type': 'Polygon'},
...     'properties': {'foo': 'bar'},
...     'type': 'Feature'}

>>> output = rewind(input)

>>> output
{'geometry': {'coordinates': [[[100, 0], [101, 0], [101, 1], [100, 1], [100, 0]]], 'type': 'Polygon'}, 'properties': {'foo': 'bar'}, 'type': 'Feature'}

>>> type(output)
<class 'dict'>

On the Console

# Enforce ring winding order on a GeoJSON file
$ rewind in.geojson > out.geojson

# fetch GeoJSON from the web and enforce ring winding order
$ curl "https://myserver.com/in.geojson" | rewind

Versioning

geojson-rewind follows semantic versioning. For this project, the "API" also includes:

  • CLI flags and options
  • CLI exit codes

In line with common practice in the python community, geojson-rewind will drop compatibility with unsupported python versions without incrementing the major version.

Acknowledgements

geojson-rewind is a python port of Mapbox's javascript geojson-rewind package. Credit to Tom MacWright and contributors.

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

geojson_rewind-1.1.0.tar.gz (4.1 kB view hashes)

Uploaded Source

Built Distribution

geojson_rewind-1.1.0-py3-none-any.whl (5.2 kB view hashes)

Uploaded Python 3

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page