[GitHub] [carbondata] ajantha-bhat commented on a change in pull request #3481: [CARBONDATA-3548]Geospatial Support： add hash id create，query condition analyze and generate hash id list

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ajantha-bhat commented on a change in pull request #3481: [CARBONDATA-3548]Geospatial Support： add hash id create，query condition analyze and generate hash id list
URL: https://github.com/apache/carbondata/pull/3481#discussion_r356547637
 
 

 ##########
 File path: geo/src/main/java/org/apache/carbondata/geo/GeoHashImpl.java
 ##########
 @@ -168,20 +238,151 @@ public String generate(List<?> sources) throws Exception {
     if (!(sources.get(0) instanceof Long) || !(sources.get(1) instanceof Long)) {
       throw new RuntimeException("Source columns must be of Long type.");
     }
-    //TODO: generate geohashId
-    return String.valueOf(0);
+    Long longitude = (Long) sources.get(0);
+    Long latitude  = (Long) sources.get(1);
+    // generate the hash code
+    int[] gridPoint = calculateID(longitude, latitude);
+    Long hashId = createHashID(gridPoint[0], gridPoint[1]);
+    return String.valueOf(hashId);
   }
 
   /**
    * Query processor for GeoHash.
-   * @param polygon
+   * example: (`LONGITUDE`, `LATITUDE`, '116270714,40112476;116217155,40028403;
+   * 116337318,39927378;116459541,39966859;116447868,40076233;116385384,40129279;')
+   * @param polygon a group of pints, close out to form an area
    * @return Returns list of ranges of GeoHash IDs
    * @throws Exception
    */
   @Override
   public List<Long[]> query(String polygon) throws Exception {
-    List<Long[]> rangeList = new ArrayList<Long[]>();
-    // TODO: process the polygon coordinates and generate the list of ranges of GeoHash IDs
-    return rangeList;
+    String[] pointList = polygon.split(";");
+    if (3  > pointList.length) {
+      throw new RuntimeException("polygon need at least 3 points, really has " + pointList.length);
+    } else {
+      List<double[]> queryList = new ArrayList<>();
+      for (String str: pointList) {
+        String[] points = str.split(",");
+        if (2 != points.length) {
+          throw new RuntimeException("longitude and latitude is a pair need 2 data");
+        } else {
+          try {
+            queryList.add(new double[] {Double.valueOf(points[0]), Double.valueOf(points[1])});
+          } catch (NumberFormatException e) {
+            throw new RuntimeException("can not covert the string data to double", e);
+          }
+        }
+      }
+      if (3 > queryList.size()) {
+        throw new RuntimeException("polygon list size" + queryList.size() + " less than three");
+      } else {
+        List<Long[]> rangeList = getPolygonRangeList(queryList);
+        return rangeList;
+      }
+    }
+  }
+
+  /**
+   * use query polygon condition to get the hash id list, the list is merged and sorted.
+   * @param queryList polygon points close out to form an area
+   * @return hash id list
+   * @throws Exception
+   */
+  private  List<Long[]> getPolygonRangeList(List<double[]> queryList) throws Exception {
+    QuadTreeCls qTreee = new QuadTreeCls(userDefineMinLongitude, userDefineMinLatitude,
+        CalculateMaxLongitude, CalculateMaxLatitude, cutLevel);
+    qTreee.insert(queryList);
+    return qTreee.getNodesData();
+  }
+
+  /**
+   *  After necessary attributes, perform necessary calculation
+   * @throws Exception
+   */
+  private void calculateData() throws Exception {
+    // Angular to radian, radians = (Math.PI / 180) * degrees
+    // Cosine value of latitude angle of origin
+    this.mCos = Math.cos(this.oriLatitude / this.conversionRatio * Math.PI / CONVERT_FACTOR);
+    // get δx=L∗360/(2πR∗cos(lat))
+    this.deltaX = (this.gridSize * 360) / (2 * Math.PI * EARTH_RADIUS * this.mCos);
+    this.deltaXByRatio = this.deltaX * this.conversionRatio;
+    // get δy=L∗360/2πR
+    this.deltaY = (this.gridSize * 360) / (2 * Math.PI * EARTH_RADIUS);
+    this.deltaYByRatio = this.deltaY * this.conversionRatio;
+    LOGGER.info("after spatial calculate delta X is: " + String.format("%f", this.deltaX)
+                    + "the delta Y is: " + String.format("%f", this.deltaY));
+    LOGGER.info("after spatial calculate X ByRatio is: " + String.format("%f", this.deltaXByRatio)
+                    + "the Y ByRatio is: " + String.format("%f", this.deltaYByRatio));
+    // Calculate the complement area and grid i,j for grid number
+    // Xmax = x0+(2^n∗δx) Ymax = y0+(2^n∗δx) Where n is the number of cut
+    // Where x0, Y0 are the minimum x, y coordinates of a given region，
+    // Xmax >= maxLongitude Ymax >= maxLatitude
+    // In the calculation process, first substitute maxlongitude and maxlatitude to calculate n.
+    // if n is not an integer, then take the next integer of N, and then substitute to find
+    // xmax and ymax。
+    this.calculateArea();
+  }
+
+  /**
+   * Calculate the complement area, including the range of the complement area, t
+   * he number of knives cut and the depth of the quad tree
+   */
+  private void calculateArea() {
+    // step 1 calculate xn, yn by using maxLongitude, maxLatitude, minLongitude, minLatitude
+    // substitution formula
+    // Here, the user's given area is mostly rectangle, which needs to be extended to
+    // square processing to find the maximum value of XN and yn
+    // n=log_2 （Xmax−X0)/δx， log_2 （Ymax−Y0)/δy
+    double Xn = Math.log((userDefineMaxLongitude - userDefineMinLongitude) / deltaX)
+                    / Math.log(2);
+    double Yn = Math.log((userDefineMaxLatitude - userDefineMinLatitude) / deltaY)
+                    / Math.log(2);
+    double doubleMax = Math.max(Xn, Yn);
+    this.cutLevel = doubleMax % 1 == 0 ? (int) doubleMax : (int) (doubleMax + 1);
+    // setep 2 recalculate the region according to the number of segmentation
 
 Review comment:
   *step

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