calibrate predator-prey model

[pedro-andrade-inpe]

Calibrate predator-prey model using MultipleRuns only. Use the current version of sysdyn in github instead of the version available in the repository. This will be a very nice example for calibration package. See the code below:

import("sysdyn")
import("calibration")

data = {
    hares = {30, 47.2, 70.2, 77.4, 36.3, 20.6, 18.1, 21.4, 22, 25.4, 27.1, 40.3, 57, 76.6, 52.3, 19.5, 11.2, 7.6, 14.6, 16.2, 24.7},
    lynx = {4, 6.1, 9.8, 35.2, 59.4, 41.7, 19, 13, 8.3, 9.1, 7.4, 8, 12.3, 19.5, 45.7, 51.1, 29.7, 15.8, 9.7, 10.1, 8.6}
}

minimum = math.huge

MultipleRuns{
    model = PredatorPrey,
    hideGraphs = true,
    parameters = {
        rabbits = data.hares[1],
        wolves = data.lynx[1],
        finalTime = 20,
        predDeath = Choice{0.001, 0.002, 0.003},
        predGrowthKills = Choice{0.00002, 0.00004, 0.00008},
        preyDeathPred = Choice{0.001, 0.002, 0.004},
        preyGrowth = Choice{0.09, 0.18, 0.36}
    },
    fit = function(model)
        sum = 0

        data.predator = model.predator
        data.prey     = model.prey
        for i = 1, 20 do
            dif = (data.predator[i] - data.lynx[i]) ^ 2 + 
                  (data.hares[i] - data.prey[i]) ^ 2

            sum = sum + dif
        end

        if sum < minimum then
            minimum = sum
            minimumModel = model
        end
    end
}

print(minimum)
print(minimumModel)

data.predator = minimumModel.predator
data.prey     = minimumModel.prey

Chart{
    data = data,
    select = {"hares", "lynx", "predator", "prey"}
}