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https://github.com/maxogden/simplify-geojson
apply the ramer-douglas-peucker line simplification to geojson features or feature collections in JS or on the CLI
https://github.com/maxogden/simplify-geojson
Last synced: 4 months ago
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apply the ramer-douglas-peucker line simplification to geojson features or feature collections in JS or on the CLI
- Host: GitHub
- URL: https://github.com/maxogden/simplify-geojson
- Owner: max-mapper
- Created: 2014-02-20T23:33:58.000Z (almost 11 years ago)
- Default Branch: master
- Last Pushed: 2022-04-12T17:08:20.000Z (almost 3 years ago)
- Last Synced: 2024-05-17T16:19:11.272Z (9 months ago)
- Language: JavaScript
- Homepage:
- Size: 67.4 KB
- Stars: 175
- Watchers: 6
- Forks: 18
- Open Issues: 4
-
Metadata Files:
- Readme: readme.md
- Contributing: contributing.md
Awesome Lists containing this project
- awesome-starred - maxogden/simplify-geojson - apply the ramer-douglas-peucker line simplification to geojson features or feature collections in JS or on the CLI (others)
README
# simplify-geojson
Apply [Ramer–Douglas–Peucker](https://en.wikipedia.org/wiki/Ramer%E2%80%93Douglas%E2%80%93Peucker_algorithm) line simplification to [GeoJSON](http://www.geojson.org/) features or feature collections in JS or on the CLI.
[](https://nodei.co/npm/simplify-geojson/)
This module uses https://github.com/seabre/simplify-geometry for the simplification and wraps it in a interface for easily simplifying GeoJSON.
## Install
```
npm install simplify-geojson
```
## Usage
### CLI
```sh
cat data.geojson | simplify-geojson -t 0.01
```
Tolerance is specified by either `-t` or `--tolerance` and is a number in degrees (e.g. lat/lon distance). 1 degree is roughly equivalent to 69 miles. the default is 0.001, which is around a city block long.
### JS
```js
var simplify = require('simplify-geojson')
var simplified = simplify(geojson, tolerance)
```
`geojson` can be any of the following:
- Feature with a LineString
- Feature with a MultiLineString
- Feature with a Polygon
- Feature with a MultiPolygon
- FeatureCollection with any of the above
All segments in any of the supported types will be simplified (including holes in polygons, for instance).
## Examples
Convert a CSV with lat/lon columns into geojson, then simplify that geojson, then open it in [geojson.io](http://geojson.io/) (CSV is from my GPS logger and was my bike commute this morning):
```sh
npm install simplify-geojson geojsonio-cli csv2geojson -g
curl https://raw.github.com/maxogden/simplify-geojson/master/test-data/oakland-route.csv | \
csv2geojson --lat "LATITUDE N/S" --lon "LONGITUDE E/W" --line true | \
simplify-geojson -t 0.001 | \
geojsonio
```
Simplify alaska's border outline and count the number of lines of the simplified geojson output (tweak `-t` to see how it affects length):
```sh
curl https://rawgit.com/johan/world.geo.json/master/countries/USA/AK.geo.json | \
simplify-geojson -t 0.01 | \
wc -l
```
## Contributing
Contributors welcome! Please read the [contributing guidelines](contributing.md) before getting started.
## License
[BSD-2-Clause](https://spdx.org/licenses/BSD-2-Clause.html)