Additional @turf/concave refactoring

packages/turf-concave/bench.js

@@ -15,9 +15,11 @@ const fixtures = fs.readdirSync(directory).map(filename => {
 /**
  * Single Process Benchmark
  *
- * issue-333: 651.884ms
- * pts1: 6.568ms
- * pts2: 476.032ms
+ * fiji: 17.973ms
+ * issue-333: 31.418ms
+ * pts1: 1.207ms
+ * pts2: 17.366ms
+ * pts3: 0.853ms
  */
 for (const {name, geojson} of fixtures) {
     const {maxEdge, units} = geojson.properties || {maxEdge: 1};
@@ -29,9 +31,11 @@ for (const {name, geojson} of fixtures) {
 /**
  * Benchmark Results
  *
- * issue-333 x 5.57 ops/sec ±10.65% (18 runs sampled)
- * pts1 x 315 ops/sec ±3.48% (70 runs sampled)
- * pts2 x 4.51 ops/sec ±2.28% (16 runs sampled)
+ * fiji x 1,513 ops/sec ±10.80% (63 runs sampled)
+ * issue-333 x 183 ops/sec ±2.41% (74 runs sampled)
+ * pts1 x 2,934 ops/sec ±2.35% (78 runs sampled)
+ * pts2 x 136 ops/sec ±3.87% (67 runs sampled)
+ * pts3 x 7,215 ops/sec ±9.04% (70 runs sampled)
  */
 const suite = new Benchmark.Suite('turf-transform-scale');
 for (const {name, geojson} of fixtures) {

packages/turf-concave/index.js

@@ -1,15 +1,12 @@
-// 1. run tin on points
-// 2. calculate length of all edges and area of all triangles
-// 3. remove triangles that fail the max length test
-// 4. buffer the results slightly
-// 5. merge the results
 var tin = require('@turf/tin');
-var union = require('@turf/union');
+var helpers = require('@turf/helpers');
 var distance = require('@turf/distance');
-var clone = require('@turf/clone');
+var dissolve = require('geojson-dissolve');
+var feature = helpers.feature;
+var featureCollection = helpers.featureCollection;
 
 /**
- * Takes a set of {@link Point|points} and returns a concave hull polygon.
+ * Takes a set of {@link Point|points} and returns a concave hull Polygon or MultiPolygon.
  * Internally, this uses [turf-tin](https://github.com/Turfjs/turf-tin) to generate geometries.
  *
  * @name concave
@@ -34,11 +31,16 @@ var clone = require('@turf/clone');
  * var addToMap = [points, hull]
  */
 module.exports = function (points, maxEdge, units) {
+    // validation
     if (!points) throw new Error('points is required');
     if (maxEdge === undefined || maxEdge === null) throw new Error('maxEdge is required');
     if (typeof maxEdge !== 'number') throw new Error('invalid maxEdge');
 
-    var tinPolys = tin(points);
+    var cleaned = removeDuplicates(points);
+
+    var tinPolys = tin(cleaned);
+    // calculate length of all edges and area of all triangles
+    // and remove triangles that fail the max length test
     tinPolys.features = tinPolys.features.filter(function (triangle) {
         var pt1 = triangle.geometry.coordinates[0][0];
         var pt2 = triangle.geometry.coordinates[0][1];
@@ -51,23 +53,32 @@ module.exports = function (points, maxEdge, units) {
 
     if (tinPolys.features.length < 1) throw new Error('too few polygons found to compute concave hull');
 
-    return merge(tinPolys.features);
+    // merge the adjacent triangles
+    var dissolved = dissolve(tinPolys.features);
+    // geojson-dissolve always returns a MultiPolygon
+    if (dissolved.coordinates.length === 1) {
+        dissolved.coordinates = dissolved.coordinates[0];
+        dissolved.type = 'Polygon';
+    }
+    return feature(dissolved);
 };
 
 /**
- * Merges/Unifies all the features in a single polygon
+ * Removes duplicated points in a collection returning a new collection
  *
  * @private
- * @param {Array<Feature>} features to be merged
- * @returns {Feature<(Polygon|MultiPolygon)>} merged result
+ * @param {FeatureCollection<Point>} points to be cleaned
+ * @returns {FeatureCollection<Point>} cleaned set of points
  */
-function merge(features) {
-    var merged = clone(features[0]);
-    merged.properties = {};
-
-    for (var i = 0, len = features.length; i < len; i++) {
-        var poly = features[i];
-        if (poly.geometry) merged = union(merged, poly);
-    }
-    return merged;
+function removeDuplicates(points) {
+    var cleaned = [];
+    var existing = {};
+    points.features.forEach(function (pt) {
+        var key = pt.geometry.coordinates.join('-');
+        if (!existing.hasOwnProperty(key)) {
+            cleaned.push(pt);
+            existing[key] = true;
+        }
+    });
+    return featureCollection(cleaned, points.properties);
 }

packages/turf-concave/package.json

@@ -24,25 +24,31 @@
   ],
   "author": "Turf Authors",
   "contributors": [
-    "Stefano Borghi <@stebogit>"
+    "Tom MacWright <@tmcw>",
+    "Lyzi Diamond <@lyzidiamond>",
+    "Denis Carriere <@DenisCarriere>",
+    "Stefano Borghi <@stebogit>",
+    "Rowan Winsemius <@rowanwins>",
+    "Daniel Pulido <@dpmcmlxxvi>",
+    "Stephen Whitmore <@noffle>",
+    "Gregor MacLennan <@gmaclennan>"
   ],
   "license": "MIT",
   "bugs": {
     "url": "https://github.com/Turfjs/turf/issues"
   },
   "homepage": "https://github.com/Turfjs/turf",
   "devDependencies": {
-    "@turf/helpers": "^4.6.0",
     "@turf/meta": "^4.6.0",
     "benchmark": "^2.1.4",
     "load-json-file": "^2.0.0",
     "tape": "^4.6.3",
     "write-json-file": "^2.1.4"
   },
   "dependencies": {
-    "@turf/distance": "^4.6.0",
-    "@turf/tin": "^4.6.0",
-    "@turf/union": "^4.6.0",
-    "@turf/clone": "^4.6.0"
+    "@turf/distance": "4.6.0",
+    "@turf/helpers": "^4.6.0",
+    "@turf/tin": "4.6.0",
+    "geojson-dissolve": "3.1.0"
   }
 }

packages/turf-concave/test.js

@@ -20,9 +20,10 @@ const fixtures = fs.readdirSync(directories.in).map(filename => {
     };
 });
 
-test('turf-line-split', t => {
+test('turf-concave', t => {
     for(const {filename, name, geojson}  of fixtures) {
-        const {maxEdge, units} = geojson.properties || {maxEdge: 1};
+        let {maxEdge, units} = geojson.properties;
+        maxEdge = maxEdge || 1;
         const hull = concave(geojson, maxEdge, units);
         featureEach(geojson, stylePt);
         const results = featureCollection([...geojson.features, hull]);
@@ -37,7 +38,7 @@ test('turf-line-split', t => {
 const points = featureCollection([point([0, 0]), point([1, 1]), point([1, 0])]);
 const onePoint = featureCollection([point([0, 0])]);
 
-test('concave', t => {
+test('concave -- throw', t => {
     t.throws(() => concave(onePoint, 5.5, 'miles'), /too few polygons found to compute concave hull/, 'too few points');
     t.throws(() => concave(onePoint, 0), /too few polygons found to compute concave hull/, 'maxEdge too small');