merge-bcn-neighborhoods.js

"use strict";
var fs = require('fs');
var path = require('path');

var _ = require('lodash');
var turf = require('turf');

var bcnByDistrict = fs.readFileSync(path.join(__dirname, 'barcelona-neighborhoods.geojson'));
var polygons = JSON.parse(bcnByDistrict);


function removeHolesFromPolygon(p) {
    p.geometry.coordinates = [p.geometry.coordinates[0]];
}
function mergeUsingTurfMerge(fc) {

    return turf.merge(fc);      // Returns a MultiPolygon. Go figure.
}
function mergeUsingTurfBuffer(fc) {
    var meters = 10;
    var buffer = turf.buffer(fc, meters/1000, 'kilometers');
    removeHolesFromPolygon(buffer.features[0]);
    return buffer;
}
function simplify(fc) {
    var tolerance = 0.001;
    fc.features = _.map(fc.features, function(pol) { 
        return turf.simplify(pol, tolerance, false); });
}


var singlePolygon = mergeUsingTurfBuffer(polygons);
singlePolygon.attribution = 'Built from https://gist.github.com/guillelopez/26f57e5966b5f8825e9b';
fs.writeFileSync(path.join(__dirname, 'barcelona.detailed.geojson'),
                 JSON.stringify(singlePolygon, null, 2));


simplify(singlePolygon);
fs.writeFileSync(path.join(__dirname, 'barcelona.simple.geojson'),
                 JSON.stringify(singlePolygon, null, 2));