Introduction to the Modeling and Analysis of Complex Systems

438 CHAPTER 19. AGENT-BASED MODELSFigure 19.2 shows the result with the neighborhood radius r=0.1 and the thresholdfor moving th = 0.5. It is clearly observed that the agents self-organize from an initiallyrandom distribution to a patchy pattern where the two types are clearly segregated fromeach other.1.01.01.00.80.80.80.60.60.60.40.40.40.20.20.20.00.0 0.2 0.4 0.6 0.8 1.00.00.0 0.2 0.4 0.6 0.8 1.00.00.0 0.2 0.4 0.6 0.8 1.0Figure 19.2: Visual output of Code 19.8. Time flows from left to right.Exercise 19.2 Conduct simulations of Schelling’s segregation model with th(threshold for moving), r (neighborhood radius), and/or n (population size = density)varied systematically. Determine the condition in which segregation occurs.Is the transition gradual or sharp?Exercise 19.3 Develop a metric that characterizes the level of segregation fromthe positions of the two types of agents. Then plot how this metric changes asparameter values are varied.Here are some other well-known models that show quite unique emergent patternsor dynamic behaviors. They can be implemented as an ABM by modifying the code forSchelling’s segregation model. Have fun!Exercise 19.4 Diffusion-limited aggregation Diffusion-limited aggregation(DLA) is a growth process of clusters of aggregated particles driven by their randomdiffusion. There are two types of particles, like in Schelling’s segregation