Examples of de.lmu.ifi.dbs.elki.math.ConvexHull2D

de.lmu.ifi.dbs.elki.math.ConvexHull2D
Classes to compute the convex hull of a set of points in 2D, using the classic Grahams scan. Also computes a bounding box. @author Erich Schubert

  protected void redraw() {
    addCSSClasses(svgp);
    DBIDSelection selContext = context.getSelection();
    if(selContext != null) {
      DBIDs selection = selContext.getSelectedIds();
      ConvexHull2D hull = new ConvexHull2D();
      for(DBID i : selection) {
        try {
          hull.add(new Vector(proj.fastProjectDataToRenderSpace(rel.get(i))));
        }
        catch(ObjectNotFoundException e) {
          // ignore
        }
      }
      Polygon chres = hull.getHull();
      if(chres != null && chres.size() >= 3) {
        SVGPath path = new SVGPath(chres);


        Element selHull = path.makeElement(svgp);
        SVGUtil.addCSSClass(selHull, SELECTEDHULL);

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    for(int cnum = 0; cnum < clustering.getAllClusters().size(); cnum++) {
      Cluster<?> clus = ci.next();


      final DBIDs ids = clus.getIDs();
      ConvexHull2D hull = new ConvexHull2D();


      for(DBID clpnum : ids) {
        double[] projP = proj.fastProjectDataToRenderSpace(rel.get(clpnum).getColumnVector());
        hull.add(new Vector(projP));
      }
      Polygon chres = hull.getHull();


      // Plot the convex hull:
      if(chres != null) {
        SVGPath path = new SVGPath(chres);
        // Approximate area (using bounding box)

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      layer.appendChild(ellipse);
    }
  }


  protected Polygon makeHull(Vector[] pc) {
    ConvexHull2D hull = new ConvexHull2D();


    Vector diag = new Vector(0, 0);
    for(int j = 0; j < pc.length; j++) {
      hull.add(pc[j]);
      hull.add(pc[j].times(-1));
      for(int k = j + 1; k < pc.length; k++) {
        Vector q = pc[k];
        Vector ppq = pc[j].plus(q).timesEquals(MathUtil.SQRTHALF);
        Vector pmq = pc[j].minus(q).timesEquals(MathUtil.SQRTHALF);
        hull.add(ppq);
        hull.add(ppq.times(-1));
        hull.add(pmq);
        hull.add(pmq.times(-1));
      }
      diag.plusEquals(pc[j]);
    }
    diag.timesEquals(1.0 / Math.sqrt(pc.length));
    hull.add(diag);
    hull.add(diag.times(-1));


    Polygon chres = hull.getHull();
    return chres;
  }

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    Polygon chres = hull.getHull();
    return chres;
  }


  protected Polygon makeHullComplex(Vector[] pc) {
    ConvexHull2D hull = new ConvexHull2D();


    Vector diag = new Vector(0, 0);
    for(int j = 0; j < pc.length; j++) {
      hull.add(pc[j]);
      hull.add(pc[j].times(-1));
      for(int k = j + 1; k < pc.length; k++) {
        Vector q = pc[k];
        Vector ppq = pc[j].plus(q).timesEquals(MathUtil.SQRTHALF);
        Vector pmq = pc[j].minus(q).timesEquals(MathUtil.SQRTHALF);
        hull.add(ppq);
        hull.add(ppq.times(-1));
        hull.add(pmq);
        hull.add(pmq.times(-1));
        for(int l = k + 1; l < pc.length; l++) {
          Vector r = pc[k];
          Vector ppqpr = ppq.plus(r).timesEquals(Math.sqrt(1 / 3.));
          Vector pmqpr = pmq.plus(r).timesEquals(Math.sqrt(1 / 3.));
          Vector ppqmr = ppq.minus(r).timesEquals(Math.sqrt(1 / 3.));
          Vector pmqmr = pmq.minus(r).timesEquals(Math.sqrt(1 / 3.));
          hull.add(ppqpr);
          hull.add(ppqpr.times(-1));
          hull.add(pmqpr);
          hull.add(pmqpr.times(-1));
          hull.add(ppqmr);
          hull.add(ppqmr.times(-1));
          hull.add(pmqmr);
          hull.add(pmqmr.times(-1));
        }
      }
      diag.plusEquals(pc[j]);
    }
    diag.timesEquals(1.0 / Math.sqrt(pc.length));
    hull.add(diag);
    hull.add(diag.times(-1));
    Polygon chres = hull.getHull();
    return chres;
  }

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Related Classes of de.lmu.ifi.dbs.elki.math.ConvexHull2D

de.lmu.ifi.dbs.elki.data.spatial.Polygon

de.lmu.ifi.dbs.elki.math.linearalgebra.Vector

de.lmu.ifi.dbs.elki.visualization.visualizers.vis2d.ClusterConvexHullVisualization

de.lmu.ifi.dbs.elki.visualization.visualizers.vis2d.EMClusterVisualization

de.lmu.ifi.dbs.elki.visualization.visualizers.vis2d.SelectionConvexHullVisualization

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