code: public static PlotCanvas plot(SparseMatrix sparse) {
          double[] lowerBound = {0, 0};
          double[] upperBound = {sparse.ncols(), sparse.nrows()};
          PlotCanvas canvas = new PlotCanvas(lowerBound, upperBound, false);
          canvas.add(new SparseMatrixPlot(sparse));
  
          canvas.getAxis(0).setLabelVisible(false);
          canvas.getAxis(0).setGridVisible(false);
          canvas.getAxis(1).setLabelVisible(false);
          canvas.getAxis(1).setGridVisible(false);
  
          return canvas;
      }
docs: Create a sparse matrix plot canvas.
  @param sparse a sparse matrix.