Overhaul approach for dissolve module (#2008)

* Overhaul approach for dissolve module * Update docs. Resolves #1806 * More tests * run prettier * remove es6 and update yarn lock * Fix trailing bracket * rerun prettier * Ditch spread operator * prettier * remove let * Finally found remaining build dodginess * add test for properties * convert multipolys to polys to avoid breaking changes * run prettier * update package versions * fix use of hasOwnProperty * run prettier * remove changes to yarn * add empty line end yarnlock * try update yarn lock again Co-authored-by: mfedderly <mdfedderly@mdfedderly.com>
Turfjs · Jul 6, 2021 · aef4d74 · aef4d74
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diff --git a/packages/turf-dissolve/README.md b/packages/turf-dissolve/README.md
@@ -9,37 +9,65 @@ Note that [mulitpolygon][2] features within the collection are not supported
 
 **Parameters**
 
--   `featureCollection` **[FeatureCollection][3]&lt;[Polygon][4]>** input feature collection to be dissolved
--   `options` **[Object][5]** Optional parameters (optional, default `{}`)
-    -   `options.propertyName` **[string][6]?** features with equals 'propertyName' in `properties` will be merged
+- `featureCollection` **[FeatureCollection][3]&lt;[Polygon][4]>** input feature collection to be dissolved
+- `options` **[Object][5]** Optional parameters (optional, default `{}`)
+  - `options.propertyName` **[string][6]?** features with equals 'propertyName' in `properties` will be merged
 
 **Examples**
 
 ```javascript
 var features = turf.featureCollection([
-  turf.polygon([[[0, 0], [0, 1], [1, 1], [1, 0], [0, 0]]], {combine: 'yes'}),
-  turf.polygon([[[0, -1], [0, 0], [1, 0], [1, -1], [0,-1]]], {combine: 'yes'}),
-  turf.polygon([[[1,-1],[1, 0], [2, 0], [2, -1], [1, -1]]], {combine: 'no'}),
+  turf.polygon(
+    [
+      [
+        [0, 0],
+        [0, 1],
+        [1, 1],
+        [1, 0],
+        [0, 0],
+      ],
+    ],
+    { combine: "yes" }
+  ),
+  turf.polygon(
+    [
+      [
+        [0, -1],
+        [0, 0],
+        [1, 0],
+        [1, -1],
+        [0, -1],
+      ],
+    ],
+    { combine: "yes" }
+  ),
+  turf.polygon(
+    [
+      [
+        [1, -1],
+        [1, 0],
+        [2, 0],
+        [2, -1],
+        [1, -1],
+      ],
+    ],
+    { combine: "no" }
+  ),
 ]);
 
-var dissolved = turf.dissolve(features, {propertyName: 'combine'});
+var dissolved = turf.dissolve(features, { propertyName: "combine" });
 
 //addToMap
-var addToMap = [features, dissolved]
+var addToMap = [features, dissolved];
 ```
 
 Returns **[FeatureCollection][3]&lt;[Polygon][4]>** a FeatureCollection containing the dissolved polygons
 
 [1]: polygon
-
 [2]: mulitpolygon
-
 [3]: https://tools.ietf.org/html/rfc7946#section-3.3
-
 [4]: https://tools.ietf.org/html/rfc7946#section-3.1.6
-
 [5]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object
-
 [6]: https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/String
 
 <!-- This file is automatically generated. Please don't edit it directly:

diff --git a/packages/turf-dissolve/bench.js b/packages/turf-dissolve/bench.js
@@ -12,24 +12,11 @@ const fixtures = fs.readdirSync(directory).map((filename) => {
   };
 });
 
-/**
- * Single Process Benchmark
- *
- * polysByProperty: 64.173ms
- * polysWithoutProperty: 44.453ms
- */
-for (const { name, geojson } of fixtures) {
-  const propertyName = geojson.propertyName;
-  console.time(name);
-  dissolve(geojson, { propertyName });
-  console.timeEnd(name);
-}
-
 /**
  * Benchmark Results
  *
- * polysByProperty x 425 ops/sec ±7.64% (73 runs sampled)
- * polysWithoutProperty x 238 ops/sec ±11.04% (59 runs sampled)
+ * polysByProperty x 6,366 ops/sec ±1.49% (89 runs sampled)
+ * polysWithoutProperty x 4,224 ops/sec ±2.34% (77 runs sampled)
  */
 const suite = new Benchmark.Suite("turf-dissolve");
 for (const { name, geojson } of fixtures) {

diff --git a/packages/turf-dissolve/index.js b/packages/turf-dissolve/index.js
@@ -1,12 +1,8 @@
-import rbush from "geojson-rbush";
-import clone from "@turf/clone";
-import overlap from "@turf/boolean-overlap";
-import turfUnion from "@turf/union";
-import lineIntersect from "@turf/line-intersect";
-import { coordAll } from "@turf/meta";
+import { featureCollection, multiPolygon, isObject } from "@turf/helpers";
 import { collectionOf } from "@turf/invariant";
-import { lineString, isObject } from "@turf/helpers";
-import { closestGreaterNumber } from "./lib/get-closest";
+import { featureEach } from "@turf/meta";
+import flatten from "@turf/flatten";
+import polygonClipping from "polygon-clipping";
 
 /**
  * Dissolves a FeatureCollection of {@link polygon} features, filtered by an optional property name:value.
@@ -15,7 +11,7 @@ import { closestGreaterNumber } from "./lib/get-closest";
  * @name dissolve
  * @param {FeatureCollection<Polygon>} featureCollection input feature collection to be dissolved
  * @param {Object} [options={}] Optional parameters
- * @param {string} [options.propertyName] features with equals 'propertyName' in `properties` will be merged
+ * @param {string} [options.propertyName] features with the same `propertyName` value will be dissolved.
  * @returns {FeatureCollection<Polygon>} a FeatureCollection containing the dissolved polygons
  * @example
  * var features = turf.featureCollection([
@@ -29,118 +25,57 @@ import { closestGreaterNumber } from "./lib/get-closest";
  * //addToMap
  * var addToMap = [features, dissolved]
  */
-function dissolve(featureCollection, options) {
+function dissolve(fc, options) {
   // Optional parameters
   options = options || {};
   if (!isObject(options)) throw new Error("options is invalid");
   var propertyName = options.propertyName;
 
   // Input validation
-  collectionOf(featureCollection, "Polygon", "dissolve");
+  collectionOf(fc, "Polygon", "dissolve");
 
   // Main
-  var fc = clone(featureCollection);
-  var features = fc.features;
-
-  var originalIndexOfItemsRemoved = [];
-
-  features.forEach(function (f, i) {
-    f.properties.origIndexPosition = i;
-  });
-  var tree = rbush();
-  tree.load(fc);
-
-  for (var i in features) {
-    var polygon = features[i];
-
-    var featureChanged = false;
-
-    tree.search(polygon).features.forEach(function (potentialMatchingFeature) {
-      polygon = features[i];
-
-      var matchFeaturePosition =
-        potentialMatchingFeature.properties.origIndexPosition;
-
+  var outFeatures = [];
+  if (!options.propertyName) {
+    return flatten(
+      multiPolygon(
+        polygonClipping.union.apply(
+          null,
+          fc.features.map(function (f) {
+            return f.geometry.coordinates;
+          })
+        )
+      )
+    );
+  } else {
+    var uniquePropertyVals = {};
+    featureEach(fc, function (feature) {
       if (
-        originalIndexOfItemsRemoved.length > 0 &&
-        matchFeaturePosition !== 0
+        !Object.prototype.hasOwnProperty.call(
+          uniquePropertyVals,
+          feature.properties[propertyName]
+        )
       ) {
-        if (
-          matchFeaturePosition >
-          originalIndexOfItemsRemoved[originalIndexOfItemsRemoved.length - 1]
-        ) {
-          matchFeaturePosition =
-            matchFeaturePosition - originalIndexOfItemsRemoved.length;
-        } else {
-          var closestNumber = closestGreaterNumber(
-            matchFeaturePosition,
-            originalIndexOfItemsRemoved
-          );
-          if (closestNumber !== 0) {
-            matchFeaturePosition = matchFeaturePosition - closestNumber;
-          }
-        }
+        uniquePropertyVals[feature.properties[propertyName]] = [];
       }
-
-      if (matchFeaturePosition === +i) return;
-
-      var matchFeature = features[matchFeaturePosition];
-      if (!matchFeature || !polygon) return;
-
-      if (
-        propertyName !== undefined &&
-        matchFeature.properties[propertyName] !==
-          polygon.properties[propertyName]
-      )
-        return;
-
-      if (
-        !overlap(polygon, matchFeature) ||
-        !ringsIntersect(polygon, matchFeature)
-      )
-        return;
-
-      features[i] = turfUnion(polygon, matchFeature);
-
-      originalIndexOfItemsRemoved.push(
-        potentialMatchingFeature.properties.origIndexPosition
-      );
-      originalIndexOfItemsRemoved.sort(function (a, b) {
-        return a - b;
-      });
-
-      tree.remove(potentialMatchingFeature);
-      features.splice(matchFeaturePosition, 1);
-      polygon.properties.origIndexPosition = i;
-      tree.remove(polygon, function (a, b) {
-        return (
-          a.properties.origIndexPosition === b.properties.origIndexPosition
-        );
-      });
-      featureChanged = true;
+      uniquePropertyVals[feature.properties[propertyName]].push(feature);
     });
-
-    if (featureChanged) {
-      if (!polygon) continue;
-      polygon.properties.origIndexPosition = i;
-      tree.insert(polygon);
-      i--;
+    var vals = Object.keys(uniquePropertyVals);
+    for (var i = 0; i < vals.length; i++) {
+      var mp = multiPolygon(
+        polygonClipping.union.apply(
+          null,
+          uniquePropertyVals[vals[i]].map(function (f) {
+            return f.geometry.coordinates;
+          })
+        )
+      );
+      mp.properties[propertyName] = vals[i];
+      outFeatures.push(mp);
     }
   }
 
-  features.forEach(function (f) {
-    delete f.properties.origIndexPosition;
-    delete f.bbox;
-  });
-
-  return fc;
-}
-
-function ringsIntersect(poly1, poly2) {
-  var line1 = lineString(coordAll(poly1));
-  var line2 = lineString(coordAll(poly2));
-  var points = lineIntersect(line1, line2).features;
-  return points.length > 0;
+  return flatten(featureCollection(outFeatures));
 }
 
 export default dissolve;
diff --git a/packages/turf-dissolve/lib/get-closest.js b/packages/turf-dissolve/lib/get-closest.js