How to get subtree from symbolic expression? in ModelingToolkit.jl

Specific Domains Modelling & Simulations
2

ModelingToolkit is built on Symbolics and SymbolicUtils, that is the place to look for low-level expression manipulation like this. Here is an example (not complete and minimally tested).

using Symbolics

function products(expr)
    ex = Symbolics.unwrap(expr)
    terms = arguments(ex)
    products = filter(terms) do t
        istree(t) && ((operation(t) == *) || (operation(t) == ^))
    end
end

julia> ex = x * y + z + z*x + y*y
z(t) + x(t)*y(t) + x(t)*z(t) + y(t)^2

julia> products(ex)
3-element Vector{Any}:
 x(t)*y(t)
 x(t)*z(t)
 y(t)^2