antimeridian

Fix shapes that cross the antimeridian. See the documentation for information about the underlying algorithm. Depends on shapely and numpy.

Can fix:

• Shapely Polygon, MultiPolygon, LineString, and MultiLineString objects
• GeoJSON Polygons, MultiPolygons, Features and FeatureCollections, as dictionaries
• Anything that has a __geo_interface__

This repo has been ported to a few other languages:

• Typescript: https://github.com/krisaoe/antimeridian-ts
• Go: https://github.com/go-geospatial/antimeridian

Usage

python -m pip install antimeridian

Then:

import antimeridian

fixed = antimeridian.fix_geojson(geojson)

Note

fix_geojson mutates the input dictionary in-place. If you need to preserve the original GeoJSON, make a copy first:

import copy
fixed = antimeridian.fix_geojson(copy.deepcopy(geojson))

We also have some utilities to create bounding boxes and centroids from antimeridian-crossing polygons and multipolygons. See the documentation for a complete API reference.

Command line interface

Use the cli optional dependency to install the antimeridian CLI:

python -m pip install 'antimeridian[cli]'
antimeridian fix input.json > output.json

Developing

Get uv. Then:

git clone https://github.com/gadomski/antimeridian
cd antimeridian
uv sync

We use pytest for tests:

uv run pytest

To build and serve the docs locally:

uv run mkdocs serve

Contributing

See CONTRIBUTING.md.

License

Apache-2.0