Scheduler errors when trying to graph agents

Specific Domains Modelling & Simulations
, ,
1

Hello,

I’ve created an agent-based model where depositor agents withdraw money from bank agents. I’m now trying to create a visual of the network by using Graphs.jl to show the banks as nodes and the depositors’ paths as the edges. The depositors can withdraw from several banks, which, I believe is why the “scheduler” error message keeps occurring. The messages include UnderVarError, scheduler not defined, and Argument Error pos when using space.

How would you suggest I fix? Or is it possible with Graphs.jl? Thank you.

Blockquote
#CREATE FUNCTION to INITIALIZE and SETUP MODEL#

Define the model initialization function

function initialize_model(; num_banks=500, num_depositors=250)
properties = Dict(
:num_banks => num_banks,
:num_depositors => num_depositors,
:num_failed_banks => 0,
:num_vulnerable_banks => 0,
:tick => 0,
)
space = GridSpace((10, 10), periodic=false)
scheduler = AgentSchedulers.fastest
model = ABM(Union{Bank, Depositor}, space; properties, scheduler=scheduler)

##Poisson distribution for x and y coordinates
xes = rand(Poisson(40), num_banks)
yes = rand(Poisson(75), num_banks)


 # Add banks to the model
for (i, (x, y)) in enumerate(zip(xes, yes))
    add_agent!(Bank(i, rand(Bool), rand(Bool), rand(), 2 * rand(), 100, rand(1:10), rand(1:3)), model; pos=(x, y))
end

# Add depositors to the model
for i in 1:num_depositors
    x, y = rand(1:10), rand(1:10)  # Random positions for depositors
    add_agent!(Depositor(num_banks + i, (x, y)), model)
end

return model

end

Initialize the model

model = initialize_model()

CREATE GRAPH WITH BANKS AS NODES AND DEPOSITORS AS EDGES

Collect all banks and depositors

banks = [a for a in allagents(model) if isa(a, Bank)]
depositors = [a for a in allagents(model) if isa(a, Depositor)]

Initialize the graph with the total number of banks

n_banks = length(banks)
g = SimpleGraph(n_banks)

Create a mapping from bank IDs to graph node indices

bank_id_to_index = Dict(bank.id => i for (i, bank) in enumerate(banks))

Add edges based on depositors

for depositor in depositors
find_bank = random_agent(model, a → isa(a, Bank) && a.vul == true && a.health == true)
if find_bank != nothing
depositor_index = bank_id_to_index[find_bank.id] # This should be the bank’s index
bank_index = bank_id_to_index[find_bank.id]
Graphs.add_edge!(g, depositor_index, bank_index)
end
end

Define the colors based on vulnerability

bank_colors = [bank.vul ? :orange : :blue for bank in banks]

Define the layout using spring_layout from GraphPlot

layout = spring_layout(g; C=1.0, MAXITER=100)

Plot the graph

gplot(g, layout=layout, nodefillc=bank_colors)

2

Please see Please read: make it easier to help you .

in particular format your post so that code is shown as code, and report actual error stactraces, not approximate ones.

3

Will do. I’ll close this post and report the error verbatim. Thank you.

4

In case your model primarily focuses on the bank/depositor network, it might be worth looking at Vahana.jl, where the model is expressed as a graph from the start, offering extensive functionality around the network structure.

For example, the code to create the network and its visualization would look like this:

using Vahana
import GraphMakie, GLMakie, NetworkLayout

struct Bank
    failed::Bool
    vulnerable::Bool
end

struct Depositor
end

struct Deposit
end

sim = ModelTypes() |>
    register_agenttype!(Bank) |>
    register_agenttype!(Depositor) |>
    register_edgetype!(Deposit) |>
    create_model("bank model") |>
    create_simulation()

banks = [ Bank(rand(Bool), rand(Bool))  for _ in 1:500 ]
bankids = add_agents!(sim, banks)

healthy = filter(b -> b[2].failed == false && b[2].vulnerable == false,
                 zip(bankids, banks) |> collect)

for d in add_agents!(sim, [ Depositor() for _ in 1:250 ])
    add_edge!(sim, d, rand(healthy)[1], Deposit())
end

finish_init!(sim)

modify_vis(state::Bank, _, _) =
    Dict(:node_color => state.vulnerable ? :orange : :blue,
         :node_marker => state.failed ? :rect : :circle)

modify_vis(state::Depositor, _, _) =
    Dict(:node_color => :black,
         :node_size => 8.0)

modify_vis(state::Deposit, _, _, _) = Dict(:edge_color => :lightgrey)

create_graphplot(sim, update_fn = modify_vis) |> display
5

Thank you very much, sfuerst! I will try it.