Improving Lab 02 & 03

[nmheim]

Lab 02

• implement rational numbers (do we have a real world use case?)
• implement ecosystem without world
  • do it bottom up with simple examples instead of top down
  • implement: types (non-parametric Wolf/Sheep/Grass, show, eats

Improvement suggestions from last year

• get rid of getters/setters (#16)

Lab 03

• quick, theoretical walk through of ⚥Sheep forward method including overloading of getproperty (and setproperty!) for ⚥Sheep:

  function Base.getproperty(s::⚥Sheep, x::Symbol)
  if x == :sex || x == :sheep
      getfield(s,x)
  else
      getfield(s.sheep,x)
  end
  end

• introduce parametric type for species/sex
• implement rest of ecosystem (immutable version?!!)

Improvement suggestions from last year

• Simplify/split last exercise in multiple parts
• explain better why we are moving to parametric types
• Previous #13: Using filter is both slow and not super straight forward in this case. We could remove hint 1 and expand on hint 2. https://github.com/JuliaTeachingCTU/Scientific-Programming-in-Julia/blob/c77e2a58969a9350d6b2df4cc88aa432fa3d188e/docs/src/lecture_02/lab.md#L372-L377
• add full solution of lab 03 (sketched below)

EcosystemCore.mates(::Animal{S,Female}, ::Animal{S,Male}) where S<:Species = true
EcosystemCore.mates(::Animal{S,Male}, ::Animal{S,Female}) where S<:Species = true
EcosystemCore.mates(::Agent, ::Agent) = false

##########  Additional functionality  ##########################################

function simulate!(world::World, iters::Int; cb=()->())
    for i in 1:iters
        world_step!(world)
        cb()
    end
end

agent_count(p::Plant) = size(p)/EcosystemCore.max_size(p)
agent_count(::Animal) = 1
agent_count(as::Vector{<:Agent}) = sum(agent_count,as)

function agent_count(w::World)
    function op(d::Dict,a::Agent{S}) where S<:Species
        n = nameof(S)
        if n in keys(d)
            d[n] += agent_count(a)
        else
            d[n] = agent_count(a)
        end
        return d
    end
    foldl(op, w.agents |> values |> collect, init=Dict{Symbol,Real}())
end

function every_nth(f::Function, n::Int)
    i = 1
    function callback(args...)
        # display(i) # comment this out to see out the counter increases
        if i == n
            f(args...)
            i = 1
        else
            i += 1
        end
    end
end