Merge pull request #556 from rowanwins/dissolve

Initial commit of turf-dissolve

packages/turf-dissolve/.npmignore

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+test
+coverage

packages/turf-dissolve/LICENSE

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+The MIT License (MIT)
+
+Copyright (c) 2016 Rowan Winsemius
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

packages/turf-dissolve/README.md

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+# turf-dissolve
+Dissolves a featurecollection of polygons based on an attribute
+
+````
+	var aggregated = turfDissolve(polys, 'combine');
+
+````

packages/turf-dissolve/index.d.ts

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+/// <reference types="geojson" />
+
+type Polygons = GeoJSON.FeatureCollection<GeoJSON.Polygon>;
+
+/**
+ * http://turfjs.org/docs.html#dissolve
+ */
+declare function dissolve(featureCollection: Polygons, propertyName?: string): Polygons;
+declare namespace dissolve { }
+export = dissolve;

packages/turf-dissolve/index.js

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+var turfUnion = require('@turf/union');
+var turfOverlaps = require('turf-overlaps');
+var turfbbox = require('@turf/bbox');
+var Rbush = require('rbush');
+var gju = require('geojson-utils');
+var getClosest = require('get-closest');
+
+/**
+ * Dissolves a FeatureCollection of polygons based on a property. Note that multipart features within the collection are not supported
+ *
+ * @name dissolve
+ * @param {FeatureCollection<Polygon>} featureCollection input feature collection to be dissolved
+ * @param {string} [propertyName] property name on which to dissolve features
+ * @returns {FeatureCollection} a FeatureCollection containing the dissolved polygons
+ * @example
+ * var features = {
+ * "type": "FeatureCollection",
+ * "features": [
+ *   {
+ *     "type": "Feature",
+ *     "properties": {
+ *       "combine": "yes"
+ *     },
+ *     "geometry": {
+ *       "type": "Polygon",
+ *       "coordinates": [[[0, 0], [0, 1], [1, 1], [1, 0], [0, 0]]]
+ *     }
+ *   },
+ *   {
+ *     "type": "Feature",
+ *     "properties": {
+ *       "combine": "yes"
+ *     },
+ *     "geometry": {
+ *       "type": "Polygon",
+ *       "coordinates": [[[0, -1], [0, 0], [1, 0], [1, -1], [0,-1]]]
+ *     }
+ *   },
+ *   {
+ *     "type": "Feature",
+ *     "properties": {
+ *       "combine": "no"
+ *     },
+ *     "geometry": {
+ *       "type": "Polygon",
+ *       "coordinates": [[[1,-1],[1, 0], [2, 0], [2, -1], [1, -1]]]
+ *     }
+ *   }
+ *  ]
+ * }
+ *
+ * var dissolved = turf.dissolve(features, 'combine');
+ *
+ * //=dissolved
+ */
+module.exports = function (featureCollection, propertyName) {
+
+    var originalIndexOfItemsRemoved = [];
+    var treeItems = [];
+    var rtree = new Rbush();
+    for (var polyIndex = 0; polyIndex < featureCollection.features.length; polyIndex++) {
+        var inputFeatureBbox = turfbbox(featureCollection.features[polyIndex]);
+        var treeObj = {
+            minX: inputFeatureBbox[0],
+            minY: inputFeatureBbox[1],
+            maxX: inputFeatureBbox[2],
+            maxY: inputFeatureBbox[3],
+            origIndexPosition: polyIndex
+        };
+        treeItems.push(treeObj);
+    }
+    rtree.load(treeItems);
+
+    for (var i = 0; i < featureCollection.features.length; i++) {
+        var polygon = featureCollection.features[i];
+
+        var polyBoundingBox = turfbbox(polygon);
+        var searchObj = {
+            minX: polyBoundingBox[0],
+            minY: polyBoundingBox[1],
+            maxX: polyBoundingBox[2],
+            maxY: polyBoundingBox[3]
+        };
+        var potentialMatchingFeatures = rtree.search(searchObj);
+
+        var featureChanged = false;
+
+        for (var searchIndex = 0; searchIndex < potentialMatchingFeatures.length; searchIndex++) {
+            polygon = featureCollection.features[i];
+
+            var matchFeaturePosition = potentialMatchingFeatures[searchIndex].origIndexPosition;
+
+            if (originalIndexOfItemsRemoved.length > 0 && matchFeaturePosition !== 0) {
+                if (matchFeaturePosition > originalIndexOfItemsRemoved[originalIndexOfItemsRemoved.length - 1]) {
+                    matchFeaturePosition = matchFeaturePosition - (originalIndexOfItemsRemoved.length);
+                } else {
+                    var closestNumber = getClosest.greaterNumber(matchFeaturePosition, originalIndexOfItemsRemoved);
+                    if (closestNumber !== 0) {
+                        matchFeaturePosition = matchFeaturePosition - closestNumber;
+                    }
+                }
+            }
+
+            if (matchFeaturePosition === i) {
+                continue;
+            }
+            var matchFeature = featureCollection.features[matchFeaturePosition];
+
+            if (typeof propertyName !== 'undefined') {
+                if (matchFeature.properties[propertyName] !== polygon.properties[propertyName]) {
+                    continue;
+                }
+            }
+
+            var overlapCheck = turfOverlaps(polygon, matchFeature);
+
+            if (!overlapCheck) {
+                var polyClone = JSON.stringify(polygon);
+                var polyBeingCheckedClone = JSON.stringify(matchFeature);
+                var linestring1 = toLinestring(JSON.parse(polyClone));
+                var linestring2 = toLinestring(JSON.parse(polyBeingCheckedClone));
+                overlapCheck = gju.lineStringsIntersect(linestring1.geometry, linestring2.geometry);
+            }
+            if (!overlapCheck) {
+                continue;
+            }
+
+            featureCollection.features[i] = turfUnion(polygon, matchFeature);
+            originalIndexOfItemsRemoved.push(potentialMatchingFeatures[searchIndex].origIndexPosition);
+            originalIndexOfItemsRemoved.sort(function (a, b) {
+                return a - b;
+            });
+
+            rtree.remove(potentialMatchingFeatures[searchIndex]);
+            featureCollection.features.splice(matchFeaturePosition, 1);
+            searchObj.origIndexPosition = i;
+            rtree.remove(searchObj, function (a, b) {
+                return a.origIndexPosition === b.origIndexPosition;
+            });
+            featureChanged = true;
+        }
+        if (featureChanged) {
+            var newBoundingBox = turfbbox(polygon);
+            rtree.insert({
+                minX: newBoundingBox[0],
+                minY: newBoundingBox[1],
+                maxX: newBoundingBox[2],
+                maxY: newBoundingBox[3],
+                origIndexPosition: i
+            });
+            i--;
+        }
+    }
+    return featureCollection;
+};
+
+function toLinestring(polygon) {
+    if (polygon === null) throw new Error('No polygon was passed');
+    polygon.geometry.type = 'LineString';
+    var flat_arr = [].concat.apply([], polygon.geometry.coordinates);
+    polygon.geometry.coordinates = flat_arr;
+    return polygon;
+}

packages/turf-dissolve/package.json

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+{
+  "name": "@turf/dissolve",
+  "version": "3.7.5",
+  "description": "Dissolves polygons based on an attribute",
+  "main": "index.js",
+  "keywords": [
+    "turf",
+    "dissolve",
+    "gis",
+    "geojson",
+    "polygon"
+  ],
+  "author": "Rowan Winsemius",
+  "license": "MIT",
+  "dependencies": {
+    "@turf/bbox": "^3.7.5",
+    "@turf/helpers": "^3.7.5",
+    "@turf/union": "^3.7.5",
+    "geojson-utils": "^1.1.0",
+    "rbush": "^2.0.1",
+    "turf-overlaps": "^1.0.3"
+  },
+  "devDependencies": {
+    "tape": "^4.6.3"
+  },
+  "types": "index.d.ts"
+}

packages/turf-dissolve/test.js

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+var turfDissolve = require('./index');
+var test = require('tape');
+var polys = require('./test/polys.json');
+var expectedOutput = require('./test/outputPolysByProperty.json');
+var expectedOutput2 = require('./test/outputPolysWithNoProperty.json');
+
+test('turf-dissolve', function (t) {
+
+    var dissolved = turfDissolve(polys, 'combine');
+    t.equal(dissolved.features.length, 3);
+    t.deepEqual(dissolved, expectedOutput);
+
+    var dissolved2 = turfDissolve(polys);
+    t.equal(dissolved2.features.length, 2);
+    t.deepEqual(dissolved2, expectedOutput2);
+
+    t.end();
+});

packages/turf-dissolve/test/outputPolysByProperty.json

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+{"type":"FeatureCollection","features":[{"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[0.5,0],[0,1],[1,1],[2,1],[2,0],[1,0],[1,-1],[0,-1],[0,0],[0.5,0]],[[1,0],[1,0.5],[0.7,0],[1,0]]]},"properties":{"combine":"yes"}},{"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[1.3458251953125,0],[2,0],[2,-1],[1.3458251953125,-1],[1.3458251953125,-1.6422311515306498],[0.68115234375,-1.6422311515306498],[0.68115234375,1.4555318956783565],[1.3458251953125,1.4555318956783565],[1.3458251953125,0]]]},"properties":{"combine":"no"}},{"type":"Feature","properties":{},"geometry":{"type":"Polygon","coordinates":[[[-0.252685546875,1.252341676699629],[-0.252685546875,1.653212936926045],[0.28564453125,1.653212936926045],[0.28564453125,1.252341676699629],[-0.252685546875,1.252341676699629]]]}}]}

packages/turf-dissolve/test/outputPolysWithNoProperty.json

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+{"type":"FeatureCollection","features":[{"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[0.5,0],[0,1],[0.68115234375,1],[0.68115234375,1.4555318956783565],[1.3458251953125,1.4555318956783565],[1.3458251953125,1],[2,1],[2,0],[2,-1],[1.3458251953125,-1],[1.3458251953125,-1.6422311515306498],[0.68115234375,-1.6422311515306498],[0.68115234375,-1],[0,-1],[0,0],[0.5,0]]]},"properties":{"combine":"yes"}},{"type":"Feature","properties":{},"geometry":{"type":"Polygon","coordinates":[[[-0.252685546875,1.252341676699629],[-0.252685546875,1.653212936926045],[0.28564453125,1.653212936926045],[0.28564453125,1.252341676699629],[-0.252685546875,1.252341676699629]]]}}]}