Agent-based network random walks for modelling the spread of a pandemic

Paul Joseph Robin

PDF: pjr.pdf

Though the aim of this was to model the spread of Sars-Cov-2 virus, no special parameters for that have been added. Hence, this random walk can be considered to be any epidemic/pandemic.

Source code: Network_Walks Other implemented models like SIR can also be found here.

G A network of maximum 15 clusters.

Terms used:-

Cluster: { class Cluster} Any population (big, small, city or even village) can be modelled as a lattice cluster of m*n nodes of some population density per node. A node can be thought of as a point in the cluster where the random walkers are free to go! (shops, malls, etc…). Density means the intial average number of people per node.

This class is just a more complicated version of corona_walk which can be found in the same repository. Once formalised, it can be used as a Python package.

Exit Policy: So an object (cluster)’s place function initialises the walkers at random positions on the lattice. If a walker is already at an exit_node, it stays there. However, any new walker coming to the exit_node is jumped to a new cluster! Each cluster has a unique exit_node. So, the graph of clusters G, has a unique one-on-one correspondence to a node!

Remove Policy: When a walker is moved to a new node of G i.e., a new cluster, his (her) infect status is upgraded to 3 (removed from cluster). {0-initial, not infected; 1-infected, sick; 2-dead;}

RESULTS

The horizontal line represents the total initial population. Clusters 1,6,9 have their infection dying out within some time [Check the time axis]. Others show an unexpected result, of infection persisting! This is due to either the infection not dying out, or an unexpected error in programming is causing the infection to persist throughout the max_timescale. { A final check revealed ?46 or so sick people remaning globally}

Issues: • The above mentioned issue remains. • For a better visualisation, the edges of graph G should be colored: red, yellow, green; depending on the number of infected people passing. • Social distancing menthods to be added by making some % of walkers inactive (infect[j]=3 or 4)

Scope: • Running this program on a cluster?, by having a large max_clusters and an appropriate node density; to give the graph G small world properties (will it show?) to model a country or even the world.