Will support polygons?

[kungfoo]

I don't quite understand. What do you mean?

[kungfoo]

Do you mean polygon queries or polygon hashes? One might work by covering the entire polygon with hashes, the other won't since the bounding boxes are bound (no pun intended) to be rectangular.

[someorz]

yes,i mean polygon hashes,To determine whether a point is in a polygon

[kungfoo]

The hashes represent subdivisions of a rectangular grid, so they are by definition rectangular. Do you know of any library that has polygon support? One was to easily (and no very smartly) do it, might be to use a big enough bounding box to include all the points of the polygon. Then use that as a query.

[dsmiley]

Using Apache Lucene's spatial-extras module, which depends on LocationTech Spatial4j & JTS dependencies, you can do this with code like this (I tried it successfully):

  public void testGeoHashes() throws IOException, ParseException {
    SpatialContext ctx = JtsSpatialContext.GEO;
    GeohashPrefixTree grid = new GeohashPrefixTree(ctx, 11);//< 1 meter == 11 maxLevels
    Shape shape = ctx.getFormats().getWktReader().read("POLYGON((-93.18100824442227 45.25676372469945," +
        "-93.23182001200654 45.21421290799412," +
        "-93.16315546122038 45.23742639412364," +
        "-93.18100824442227 45.25676372469945))");
    double distErr = SpatialArgs.calcDistanceFromErrPct(shape, 0.10, ctx);
    int detailLevel = grid.getLevelForDistance(distErr);
    CellIterator cellIterator = grid.getTreeCellIterator(shape, detailLevel);
    BytesRef bytesRef = new BytesRef();
    while (cellIterator.hasNext()) {
      Cell next = cellIterator.next();
      if (!next.isLeaf()) {
        continue;
      }
      System.out.println(next.getTokenBytesNoLeaf(bytesRef).utf8ToString());
    }

  }

The spatial-extras module of Lucene uses these grids for spatial indexes on terms.

[kungfoo]

You would have to write a small class that basically covers the polygon with rectangles (hashes) and then use these as a query. As of now, I don't have the time or resources to do that, but I'm always. open to contributions.