At each time step, a human moves to a nearby unoccupied space, and a zombie moves to the nearest human. If a zombie and an uninoculated human occupy the same space, a fierce battle ensues, in which the probability that the human will kill the zombie is pkH-z, and the probability that the zombie kills the human and converts them to their horrific undead form is pkZ-h.Zombies, however, are not attracted to inoculated humans and ignore them. If recovery? is enabled, then there is a chance (given by recoveryRate) that a zombified person will see the errors of their cannibalistic ways and return to human form. All these factors working together provide some interesting population dynamics, illustrated by the “Totals” population count plot on the screen.
For those Geographical Information Science (GIS) and Agent-Based Modeling (ABM) wonks out there, you might appreciate Dr. Andrew Crooks’ simple agent-based model of zombie attack.
Dr. Crooks, an Assistant Professor in the Department of Computational Social Science and a researcher in the Center for Social Complexity at George Mason University‘s Krasnow Institute for Advanced Study, explains this model: