concave_hull.js

#!/usr/bin/env node

var fs = require('fs');
var turf = require('@turf/turf');

function readFile(path) {
    console.log("Reading:", path);
    var data = fs.readFileSync(path);
    return JSON.parse(data);
}

function writeFile(data, path) {
    console.log("Writing:", path);
    fs.writeFileSync(path, JSON.stringify(data, null, 2));
}

function writeOutput(points, hull, path) {
    if (!hull) {
        console.log("Cannot write", path, "because hull is undefined");
        return;
    }
    var resultFeatures = points.features.concat(hull);
    var result = {
      "type": "FeatureCollection",
      "features": resultFeatures
    };
    writeFile(result, path);
}

var points = readFile('./points_dc.geojson');

var convexHull = turf.convex(points);
writeOutput(points, convexHull, './convex.geojson');

var concaveHull = turf.concave(points);
writeOutput(points, concaveHull, './concave_default.geojson');

var options = {'maxEdge': 1, 'units': 'miles'};
var concaveHull_1 = turf.concave(points, options);
writeOutput(points, concaveHull_1, './concave_1.geojson');

options = {'maxEdge': 0.1, 'units': 'miles'};
var concaveHull_point1 = turf.concave(points);
writeOutput(points, concaveHull_point1, './concave_0.1.geojson');

// Print the points
/*
points.features.forEach((pt) => {
    console.log(pt.geometry.coordinates);
});

hull.geometry.coordinates.forEach((polygon, index) => {
    console.log("Polygon", index);
    polygon.forEach((point, index) => {
        console.log("Point", index, point);
    });
});
*/

gistfile1.txt

#!/usr/bin/env node

var fs = require('fs');
var turf = require('@turf/turf');

function readFile(path) {
    console.log("Reading:", path);
    var data = fs.readFileSync(path);
    return JSON.parse(data);
}

function writeFile(data, path) {
    console.log("Writing:", path);
    fs.writeFileSync(path, JSON.stringify(data, null, 2));
}

function writeOutput(points, hull, path) {
    if (!hull) {
        console.log("Cannot write", path, "because hull is undefined");
        return;
    }
    var resultFeatures = points.features.concat(hull);
    var result = {
      "type": "FeatureCollection",
      "features": resultFeatures
    };
    writeFile(result, path);
}

var points = readFile('./points_dc.geojson');

var convexHull = turf.convex(points);
writeOutput(points, convexHull, './convex.geojson');

var concaveHull = turf.concave(points);
writeOutput(points, concaveHull, './concave_default.geojson');

var options = {'maxEdge': 1, 'units': 'miles'};
var concaveHull_1 = turf.concave(points, options);
writeOutput(points, concaveHull_1, './concave_1.geojson');

options = {'maxEdge': 0.1, 'units': 'miles'};
var concaveHull_point1 = turf.concave(points);
writeOutput(points, concaveHull_point1, './concave_0.1.geojson');

// Print the points
/*
points.features.forEach((pt) => {
    console.log(pt.geometry.coordinates);
});

hull.geometry.coordinates.forEach((polygon, index) => {
    console.log("Polygon", index);
    polygon.forEach((point, index) => {
        console.log("Point", index, point);
    });
});
*/