Movement Model Library

A quick reference to the movement models included in epymorph.

Primary models

The models we think are most helpful to real-world modeling efforts.

Centroids

The centroids MM describes a basic commuter movement where a fixed proportion of the population commutes every day, travels to another location for 1/3 of a day (with a location likelihood that decreases with distance), and then returns home for the remaining 2/3 of the day.

  • tau steps: (0.333, 0.667)
  • clauses: CentroidsClause

Flat

This model evenly weights the probability of movement to all other nodes. It uses parameter ‘commuter_proportion’ to determine how many people should be moving, based on the total normal population of each node.

  • tau steps: (0.333, 0.667)
  • clauses: FlatClause

No

No movement at all. This is handy for cases when you want to disable movement in an experiment, or for testing.

  • tau steps: (1,)
  • clauses: NoClause

Pei

Modeled after the Pei influenza paper, this model simulates two types of movers – regular commuters and more-randomized dispersers. Each is somewhat stochastic but adhere to the general shape dictated by the commuters array. Both kinds of movement can be “tuned” through their respective parameters: move_control and theta.

  • tau steps: (0.333, 0.667)
  • clauses: Commuters, Dispersers

Sparsemod

Modeled after the SPARSEMOD COVID-19 paper, this model simulates movement using a distance kernel parameterized by phi, and using a commuters matrix to determine the total expected number of commuters.

  • tau steps: (0.333, 0.667)
  • clauses: SparsemodClause

Debug models

These models are probably not useful for most real-world modeling, and exist mainly to support the testing and debugging of epymorph.

Icecube

A toy example: ice cube tray movement movement model Each state sends a fixed number of commuters to the next state in the line (without wraparound).

  • tau steps: (0.5, 0.5)
  • clauses: IcecubeClause