https://github.com/mikolalysenko/planar-graph-to-polyline

Convert a planar graph to a collection of nested polylines
https://github.com/mikolalysenko/planar-graph-to-polyline

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Convert a planar graph to a collection of nested polylines

• Host: GitHub
• URL: https://github.com/mikolalysenko/planar-graph-to-polyline
• Owner: mikolalysenko
• License: mit
• Created: 2014-04-22T18:17:42.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2021-07-15T15:43:34.000Z (over 3 years ago)
• Last Synced: 2024-04-28T14:45:27.463Z (8 months ago)
• Language: JavaScript
• Size: 11.7 KB
• Stars: 5
• Watchers: 3
• Forks: 4
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
planar-graph-to-polyline

========================

Converts a planar graph to a collection of nested polylines (as would be consumed in a GeoJSON/TopoJSON file for example).

# Example

```javascript

var graphToPolygons = require("planar-graph-to-polyline")

var edges = []

var positions = []

for(var i=1; i<=3; ++i) {

  var v0 = positions.length

  for(var j=0; j<10; ++j) {

    var theta = 2.0 * Math.PI * j / 10

    positions.push([ i * Math.cos(theta), i * Math.sin(theta) ])

    edges.push([ v0+j, v0+((j+1)%10) ])

  }

}

console.log(graphToPolygons(edges, positions))

```

Output:

```javascript

[ [ [ 20, 29, 28, 27, 26, 25, 24, 23, 22, 21 ],

    [ 11, 12, 13, 14, 15, 16, 17, 18, 19, 10 ] ],

  [ [ 0, 9, 8, 7, 6, 5, 4, 3, 2, 1 ] ] ]

```

# Install

```

npm install planar-graph-to-polyline

```

# API

#### `require("planar-graph-to-polyline")(edges, positions)`

Converts a planar graph into a collection of nested polylines

* `edges` are the edges of the graph

* `positions` are the locations of the vertices in the plane

**Returns** A list of loops encoding the regions bounded by the graph

# Credits

(c) 2014 Mikola Lysenko. MIT License