This application reads a valid geojson FeatureCollection and returns a valid geojson FeatureColleciton of centroids.
In the output:
- All properties are retained.
- Polygon features become points that represent the Polygon's centroid.
- LineString features become points that represent the middle of the LineString.
- Point features do not change.
- I have no idea how this handles MultiPolygons.
This is a Flask application that uses the Shapely Python library by @sgillies. Issues and pull requests welcome!
The service can be accessed in two ways: an upload/download page and a web service.
The upload/download page can be found here. It is pretty self explanatory.
The web service lives at http://centroids.herokuapp.com/centroids. You can post to it with geojson.
Here is an example of how you might do that from the command line with curl (example from @invisiblefunnel):
$ curl -X POST -H "Content-Type: application/json" -d \
'{
"type": "FeatureCollection",
"features": [
{
"type": "Feature",
"properties": {},
"geometry": {
"type": "Polygon",
"coordinates": [
[
[
-80.93490600585938,
35.263561862152095
],
[
-80.69320678710938,
35.32745068492882
],
[
-80.60531616210938,
35.14124815600257
],
[
-80.83328247070312,
35.06597313798418
],
[
-80.93490600585938,
35.263561862152095
]
]
]
}
}
]
}' http://centroids.herokuapp.com/centroids
Should return:
{
"features": [
{
"geometry": {
"coordinates": [
-80.76829071683488,
35.199632857787904
],
"type": "Point"
},
"properties": {},
"type": "Feature"
}
],
"type": "FeatureCollection"
}
Optionally create a virtual environment
virtualenv venv
source venv/bin/activate
Install requirements
pip install -r requirements.txt
Start the server
python hello.py
You should now be able to visit the application at http://127.0.0.1:5000/.
To run on Heroku requires a third party BUILDPACK for Heroku