geojsoncontour

geojsoncontour

A Python 3 module to convert matplotlib contour plots to geojson. Supports both contour and contourf plots.

Designed to show geographical contour plots, created with matplotlib/pyplot, as vector layer on interactive slippy maps like OpenLayers and Leaflet.

Demo project that uses geojsoncontour: climatemaps.romgens.com

Installation

Install with pip,

pip install geojsoncontour

Usage

Use contour_to_geojson to create a geojson with contour lines from a matplotlib.contour plot (not filled). Use contourf_to_geojson to create a geojson with filled contours from a matplotlib.contourf plot.

Contour plot to geojson

import numpy
import matplotlib.pyplot as plt
import geojsoncontour

# Create contour data lon_range, lat_range, Z
<your code here>

# Create a contour plot plot from grid (lat, lon) data
figure = plt.figure()
ax = figure.add_subplot(111)
contour = ax.contour(lon_range, lat_range, Z, cmap=plt.cm.jet)

# Convert matplotlib contour to geojson
geojson = geojsoncontour.contour_to_geojson(
    contour=contour,
    ndigits=3,
    unit='m'
)

For filled contour plots (matplotlib.contourf) use contourf_to_geojson. See example_contour.py and example_contourf.py for simple but complete examples.

Show the geojson on a map

An easy way to show the generated geojson on a map is the online geojson renderer geojson.io or geojson.tools.

Style properties

Stroke color and width are set as geojson properties following https://github.com/mapbox/simplestyle-spec.

Create geojson tiles

Try geojson-vt or tippecanoe if performance is an issue and you need to tile your geojson contours.

Development

Tests

Run all tests,

python -m unittest discover

Release

Install setuptools, wheel and twine:

python -m pip install --upgrade setuptools wheel twine

Increase the version number in setup.py.

Create dist:

python setup.py sdist bdist_wheel

Upload:

twine upload dist/*