morgan herlocker

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Merging Polygons with node.js

Merging a set of polygons with turf is pretty straight forward.

  1. Get your polygon features into a feature collection like so:

  2. Load the file into memory with node's fs module:

    var require('turf')
    
    // load countries
    t.load('./countries.geojson', function(err, countries){
    
    })
    
  3. call turf's merge function:

    t.merge(countries, function(err, world){
    
    })
    
  4. Lastly, write the file to disc or display it somewhere. Here it is all together:

    var t = require('turf'),
       fs = require('fs')
    
    // load countries
    t.load('./countries.geojson', function(err, countries){
     // merge the feature collection
     t.merge(countries, function(err, world){
       // write out the file
       fs.writeFile('./world.geojson', JSON.stringify(world), function(err){
         console.log('presto!')
       })
     })
    })
    

And here is the result:

I packaged this all up into a github repo if you want to clone it an try it out. To test out the code do:

git clone https://github.com/morganherlocker/turf-world-merge.git
cd turf-world-merge
npm install
node index.js

1-30-14