Coloring Voronoi cells in Delaunay Triangulations by area

General Usage
1

I have a set of points which I have used the DelaunayTriangulation Package to generate voronoi cells. I have calculated the are of each cell, and now I want to color each cell according to the area. When I read the voronoiplot() documentation I know I can pass a color argument using color=, and I know DelaunayTriangulation uses CairoMakie. Can I just manually make a list of colors normalized by each cells area and pass that in? I don’t think I am constructing my color argument correctly!

I know I can also use the voronoicells package, but I want to clip my tessellations to the convex hull so DelaunayTriangulation is the best package for me!

2

Suppose that the voronoi diagram has n polygons and you have computed their area (here as a vector). If you saved areas in a different container, then you should adapt the following lines of code
to your setup.
To compare visually the area of polygons, it is recommended to use a colorscheme, not an arbitrary collection of colors.

area =2.5 .+3.2*rand(15)
amax, amin=extrema(area)
cs=ColorSchemes.haline
polygon_colors = [get(cs, (a-amin)/(amax-amin)) for a in area]

I expect that voronoiplot can use these colors for your polygons.
I haven’t installed Makie to ckeck how voronoiplot works.

1 Like
3

Ok this is what I was looking for! I calculated the areas and then performed an inverse normal transform on them so that the values could easily be used for a colorscale…Ill try this out and let you know how it goes

4

I believe you can also pass :extrema to get to simplify a bit, e.g.

using DelaunayTriangulation, CairoMakie, ColorSchemes
tri = triangulate_rectangle(0, 1, 0, 1, 10, 10)
vorn = voronoi(tri, true)
areas = get_area.(Ref(vorn), 1:num_polygons(vorn))
colors = get(cgrad(:haline), areas, :extrema)
voronoiplot(vorn, color=colors)

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