Build contours from irregular and unsorted data

[tbreloff]

I'm starting to look at incorporating generalized contours into my package Plots.jl, but I'm a little unsure if I can do what I want:

Lets suppose I have 3 vectors:

x = rand(n)
y = rand(n)
z = x .* y

Is is possible (with Contour.jl) to extract contour coordinates for the contour lines directly from these vectors? Or do I need to preprocess the data onto some regular grid and pass a dense matrix with the heights?

I spent just a couple minutes googling, and it seems reasonable to implement something like distance-weighted least squares to preprocess the data into a mesh. If this doesn't exist, and I implement it, would you like me to submit a PR?

[darwindarak]

Contour.jl does not have anything like that right now. A PR for that would definitely be welcome!

[asinghvi17]

Makie does something similar with DelaunayTriangulation.jl. Maybe that could be a separate "backend" for Contour.jl, via an extension?