circle                  generating a circle
draw_2d_venn            draw 2d, 3d, and 4d venn diagram
ggVennDiagram           ggVennDiagram
multi                   Performs set union/intersection/diff on more
                        than two vectors.
multi_st_fun            Perform geometric set intersection, difference,
                        and union with more than two simple feature
                        geometry collections
plot_venn               plot codes
two_dimension_circle_regions
                        coordinations of polygon regions/centers for
                        venn diagram
two_dimension_region_values
                        calculating intersection values of venn
