update to 0.2.7

add spatial union

package.json

@@ -4,6 +4,7 @@
     "build:wasm": "node tools/binary-to-json src/jsgeoda.wasm > src/jsgeoda-wasm.json",
     "build:bundle": "webpack",
     "build": "npm run build:wasm && npm run build:bundle",
+    "test-local": "npm run build && cp lib/index.js ~/unfolded/platform/node_modules/@geodacenter/jsgeoda/lib/index.js",
     "serve": "http-server",
     "start": "npm run build && npm run serve",
     "doc": "jsdoc -d docs --configure jsconf.json --readme README.md",
@@ -33,7 +34,7 @@
     "webpack-cli": "^4.7.0",
     "worker-loader": "^3.0.8"
   },
-  "version": "0.2.6",
+  "version": "0.2.7",
   "description": "A javascript library for spatial data analysis",
   "main": "./lib/index.js",
   "repository": {

src/geoda-proxy.js

@@ -278,6 +278,37 @@ export default class GeoDaWasm {
     return GeoDaWasm.parseVecDouble(counts);
   }
 
+  /**
+   * Spatial union 
+   * @param {String} mapUid 
+   * @returns {Object}
+   */
+  spatialUnion(mapUid) {
+    if (!this.checkMapUid(mapUid)) return null;
+    const mp = this.wasm.spatial_union(mapUid);
+    const xx = mp.get_x();
+    const yy = mp.get_y();
+    const parts = mp.get_parts();
+
+    let i = 0;
+    let j = 0;
+    const n = xx.size();
+    let count = 0;
+    const multiPolygon = [];
+
+    while (i < n) {
+      if (i === count) {
+        multiPolygon.push([[]]);
+        count += parts.get(j);
+        j += 1;
+      }
+      multiPolygon[j - 1][0].push([xx.get(i), yy.get(i)]);
+      i += 1;
+    }
+    const tmpGeojson = { type: 'Feature', geometry: { type: 'MultiPolygon', coordinates: multiPolygon }, properties: {} };
+    return tmpGeojson;
+  }
+
   /**
    * Get the column names of the geojson map
    * @param {String} mapUid  A unique map id.