iter_agent_groups broken in v7

[Jonas-a-Zimmermann]

Update 7 broke the iter_agent_groups functionallity.
works fine in 6.2.10.

Minimal Working Example

using Agents, StaticArrays
TESTSYSTEMSIZE = 10.

@kwdef mutable struct TestAgent <: AbstractAgent
    id::Int
    pos::SVector{2,Float64}
    vel::SVector{2,Float64} = SVector(0., 0.)
end

test_space = ContinuousSpace((TESTSYSTEMSIZE, TESTSYSTEMSIZE))
model_step!(model) = nothing
test_model = StandardABM(TestAgent, test_space; model_step!)

#direct adding leads to correct position
add_agent!(SVector(0.5, 0.5), TestAgent, test_model)
add_agent!(SVector(0.5, 0.1), TestAgent, test_model)

iter_agent_groups(2, test_model)

Errors with:

ERROR: LoadError: map is not defined on sets
Stacktrace:
 [1] error(s::String)
   @ Base ./error.jl:35
 [2] map(f::Function, ::Base.KeySet{Int64, Dict{Int64, TestAgent}})
   @ Base ./abstractarray.jl:3402
 [3] (::Agents.var"#65#67"{typeof(Agents.Schedulers.fastest), StandardABM{…}})(::Int64)
   @ Agents ./none:0
 [4] iterate
   @ ./generator.jl:48 [inlined]
 [5] iter_agent_groups(order::Int64, model::StandardABM{…})
   @ Agents ~/.julia/packages/Agents/5W3YX/src/core/higher_order_iteration.jl:12
 [6] top-level scope
   @ ~/***/iter_agent_groups.jl:19
 [7] include(fname::String)
   @ Main ./sysimg.jl:38
 [8] top-level scope
   @ REPL[2]:1

Agents.jl version
[46ada45e] Agents v7.0.2

Julia version
1.11.5

[Datseris]

Thank you. When this is fixed the MWE should be added as a test!

[Jonas-a-Zimmermann]

Issue arises due to the fastest Scheduler returning a Set rather than a Vector.

┌ Info: info: fastest scheduler returns:
│   scheduler(test_model) =
│    KeySet for a Dict{Int64, TestAgent} with 2 entries. Keys:
│      2
└      1
┌ Info: info: ByID scheduler returns:
│   scheduler(test_model) =
│    2-element Vector{Int64}:
│     1
└     2

Is this intended?

[Datseris]

Yes, because otherwise it wouldn't be the fastest. It is return the keys of a dictionary. I guess map is not defined on them...? We need to change the iter_agent_groups to call Vector on the output of the scheduler if it is fastest.

[Jonas-a-Zimmermann]

I'd do something like

function iter_agent_groups(::Val{N}, model::ABM; scheduler=abmscheduler(model)) where {N}
    base_iter = Iterators.map(i -> model[i], scheduler(model))
    iters = ntuple(_ -> base_iter, Val(N))
    return Iterators.product(iters...)
end

iter_agent_groups(order::Int, model::ABM; scheduler=abmscheduler(model)) = iter_agent_groups(Val(order), model; scheduler)

which works for both the fastest and ByID scheduler - the Val version for stack access via ntuple and the wrapper for api conformity.

if you are happy with that I can open a PR tomorrow.

[Datseris]

sure, go ahead!