voronoiplot

voronoiplot(x, y, values; kwargs...)
voronoiplot(values; kwargs...)
voronoiplot(x, y; kwargs...)
voronoiplot(positions; kwargs...)
voronoiplot(vorn::VoronoiTessellation; kwargs...)

Generates and plots a Voronoi tessalation from heatmap- or point-like data. The tessellation can also be passed directly as a VoronoiTessellation from DelaunayTriangulation.jl.

Attributes

  • show_generators = true determines whether to plot the individual generators.

  • markersize = 12 sets the size of the points.

  • marker = :circle sets the shape of the points.

  • markercolor = :black sets the color of the points.

  • strokecolor = :black sets the strokecolor of the polygons.

  • strokewidth = 1 sets the width of the polygon stroke.

  • color = automatic sets the color of the polygons. If automatic, the polygons will be individually colored according to the colormap.

  • unbounded_edge_extension_factor = 0.1 sets the extension factor for the unbounded edges, used in DelaunayTriangulation.polygon_bounds.

  • clip::Union{Automatic, Rect2, Circle, Tuple} = automatic sets the clipping area for the generated polygons which can be a Rect2 (or BBox), Tuple with entries (xmin, xmax, ymin, ymax) or as a Circle. Anything outside the specified area will be removed. If the clip is not set it is automatically determined using unbounded_edge_extension_factor as a Rect.

Color attributes

  • colormap::Union{Symbol, Vector{<:Colorant}} = :viridis sets the colormap that is sampled for numeric colors. PlotUtils.cgrad(...), Makie.Reverse(any_colormap) can be used as well, or any symbol from ColorBrewer or PlotUtils. To see all available color gradients, you can call Makie.available_gradients().

  • colorscale::Function = identity color transform function. Can be any function, but only works well together with Colorbar for identity, log, log2, log10, sqrt, logit, Makie.pseudolog10 and Makie.Symlog10.

  • colorrange::Tuple{<:Real, <:Real} sets the values representing the start and end points of colormap.

  • nan_color::Union{Symbol, <:Colorant} = RGBAf(0,0,0,0) sets a replacement color for color = NaN.

  • lowclip::Union{Nothing, Symbol, <:Colorant} = nothing sets a color for any value below the colorrange.

  • highclip::Union{Nothing, Symbol, <:Colorant} = nothing sets a color for any value above the colorrange.

  • alpha = 1.0 sets the alpha value of the colormap or color attribute. Multiple alphas like in plot(alpha=0.2, color=(:red, 0.5), will get multiplied.

Examples

A voronoiplot generates a cell for each passed position similar to heatmap, however the cells are not restricted to a rectangular shape. It can be called with point based (like scatter or lines) or heatmap-like inputs.

using CairoMakie

using Random
Random.seed!(1234)


f = Figure(resolution=(1200, 450))
ax = Axis(f[1, 1])
voronoiplot!(ax, rand(Point2f, 50))

ax = Axis(f[1, 2])
voronoiplot!(ax, rand(10, 10), rand(10, 10), rand(10, 10))
f

voronoiplot uses the Voronoi tessellation from DelaunayTriangulation.jl to generate the cells. You can also do this yourself and directly plot the VoronoiTessellation object returned.

using CairoMakie
using DelaunayTriangulation

using Random
Random.seed!(1234)

points = rand(2, 50)
tri = triangulate(points)
vorn = voronoi(tri)
f, ax, tr = voronoiplot(vorn)
f

When considering standard tessellations the unbounded polygons are clipped at a bounding box determined automatically by default, or from a user-provided clipping shape (a rectangle or circle). The automatic bounding box is determined by the bounding box of generators of the tessellation, meaning the provided points, extended out by some factor unbounded_edge_extension_factor (default 0.1) proportional to the lengths of the bounding box's sides.

using CairoMakie
using DelaunayTriangulation

using Random
Random.seed!(1234)

z = LinRange(0, 1, 250) .* exp.(LinRange(0, 16pi, 250) .* im)
f, ax, tr = voronoiplot(real(z), imag(z), unbounded_edge_extension_factor = 0.4, markersize = 7)
f

using CairoMakie
using DelaunayTriangulation

using Random
Random.seed!(1234)

x = LinRange(0, 16pi, 50)
y = sin.(x)
bb = BBox(-1, 16pi + 1, -30, 30) # (xmin, xmax, ymin, ymax)
f, ax, tr = voronoiplot(x, y, show_generators=false,
    clip=bb, color=:white, strokewidth=2)
f

For clipped and centroidal tessellations, there are no unbounded polygons.

using CairoMakie
using DelaunayTriangulation

using Random
Random.seed!(1234)

points = [(0.0, 0.0), (1.0, 0.0), (1.0, 1.0), (0.0, 1.0)]
tri = triangulate(points)
refine!(tri; max_area = 0.001)
vorn = voronoi(tri, true)
f, ax, tr = voronoiplot(vorn, show_generators = true, markersize = 13, marker = 'x')
f

using CairoMakie
using DelaunayTriangulation

using Random
Random.seed!(1234)

angles = range(0, 2pi, length = 251)[1:end-1]
x = cos.(angles)
y = sin.(angles)
points = tuple.(x, y)
tri = triangulate(points)
refine!(tri; max_area = 0.001)
vorn = voronoi(tri, true)
smooth_vorn = centroidal_smooth(vorn)
f, ax, tr = voronoiplot(smooth_vorn, show_generators=false)
f