Money distribution simulation

money.jl

struct MoneySim
    balance::Array{Int64}
    members::Int64
end

function init(;members::Int64=1000, initial_balance::Int64=100)::MoneySim
    return MoneySim(fill(initial_balance, members), members)
end

function step!(self::MoneySim)
    pass_to = fill(-1, self.members)

    all_member = 1:self.members

    for i in all_member
        if self.balance[i] > 0
            pass_to[i] = rand(all_member)
        end
    end

    for i in all_member
        if pass_to[i] >= 0
            self.balance[i] -= 1
            self.balance[pass_to[i]] += 1
        end
    end
end

using Plots
function draw(self::MoneySim, i::Int64; bins=:auto)
    histogram(self.balance, bins=bins, normalize=true, xlims=(0, 400), ylims=(0,0.05), annotations=(300, 0.04, "i = $i"))
end

sim = init(members=1000)

@gif for i in 1:5000
    step!(sim)
    draw(sim, i, bins=range(0, 400, length=20))
end every 10

Inspired from https://twitter.com/masui/status/1436514323052969987

Result