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https://github.com/NickCis/polygonize
Javascript Implementation of GEOS's Polygonize function
https://github.com/NickCis/polygonize
Last synced: 18 days ago
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Javascript Implementation of GEOS's Polygonize function
- Host: GitHub
- URL: https://github.com/NickCis/polygonize
- Owner: NickCis
- License: mit
- Created: 2017-05-28T19:56:34.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2017-11-24T01:57:46.000Z (almost 7 years ago)
- Last Synced: 2024-09-29T23:16:14.743Z (about 1 month ago)
- Language: JavaScript
- Size: 87.9 KB
- Stars: 18
- Watchers: 4
- Forks: 3
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Polygonize
[](https://travis-ci.org/NickCis/polygonize)
Polygonizes a set of Geometrys which contain linework that represents the edges of a planar graph. It's basically an implementation of [GEOS's Polygonizer](https://github.com/echoz/xlibspatialite/blob/master/geos/include/geos/operation/polygonize/Polygonizer.h).
Although, the algorithm is the same as GEOS, it isn't a literal transcription of the C++ source code. It was rewriten in order to get a more javascript like code.
## JSDoc
```javascript
/**
* Polygonizes {@link LineString|(Multi)LineString(s)} into {@link Polygons}.
*
* Implementation of GEOSPolygonize function (`geos::operation::polygonize::Polygonizer`).
*
* Polygonizes a set of lines that represents edges in a planar graph. Edges must be correctly
* noded, i.e., they must only meet at their endpoints.
*
* The implementation correctly handles:
*
* - Dangles: edges which have one or both ends which are not incident on another edge endpoint.
* - Cut Edges (bridges): edges that are connected at both ends but which do not form part of a polygon.
*
* @name polygonize
* @param {FeatureCollection|Geometry|Feature} geoJson Lines in order to polygonize
* @returns {FeatureCollection} Polygons created
* @throws {Error} if geoJson is invalid.
*/
```
## Example
This example is the test found in [`test/in/complex.geojson`](https://github.com/NickCis/polygonize/blob/master/test/in/complex.geojson).
```javascript
const polygonize = require('polygonize'),
fs = require('fs'),
input = JSON.parse(fs.readFileSync('./test/in/complex.geojson'));
console.log(JSON.stringify(polygonize(input)));
```
The [input](https://github.com/NickCis/polygonize/blob/master/test/in/complex.geojson) as GeoJson LineString:
Turned into [polygons](https://github.com/NickCis/polygonize/blob/master/test/out/complex.geojson):
## Documentation
Polygonizes [(Multi)LineString(s)](http://geojson.org/geojson-spec.html#linestring) into [Polygons](Polygons).
Implementation of GEOSPolygonize function (`geos::operation::polygonize::Polygonizer`).
Polygonizes a set of lines that represents edges in a planar graph. Edges must be correctly noded, i.e., they must only meet at their endpoints.
The implementation correctly handles:
- Dangles: edges which have one or both ends which are not incident on another edge endpoint.
- Cut Edges (bridges): edges that are connected at both ends but which do not form part of a polygon.
**Parameters**
- `geojson` **([FeatureCollection](http://geojson.org/geojson-spec.html#feature-collection-objects) \| [Geometry](http://geojson.org/geojson-spec.html#geometry) \| [Feature](http://geojson.org/geojson-spec.html#feature-objects)<([LineString](http://geojson.org/geojson-spec.html#linestring) \| [MultiLineString](http://geojson.org/geojson-spec.html#multilinestring))>)** Lines in order to polygonize
- Throws **[Error](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Error)** if geoJson is invalid.
Returns **[FeatureCollection](http://geojson.org/geojson-spec.html#feature-collection-objects)<[Polygon](http://geojson.org/geojson-spec.html#polygon)>** Polygons created
### Installation
Install this module individually:
```sh
$ npm install polygonize
```