.simList-class: The `simList` class

Description

Contains the minimum components of a SpaDES simulation. Various slot accessor methods (i.e., get and set functions) are provided (see 'Accessor Methods' below).

Arguments

Slots

modules: List of character names specifying which modules to load.
params: Named list of potentially other lists specifying simulation parameters.
events: The list of scheduled events (i.e., event queue), as a data.table. See 'Event Lists' for more information.
current: The current event, as a data.table. See 'Event Lists' for more information..
completed: The list of completed events, as a data.table. See 'Event Lists' for more information.
depends: A .simDeps list of .moduleDeps objects containing module object dependency information.
simtimes: List of numerical values describing the simulation start and end times; as well as the current simulation time.
inputs: A list of length 2, containing: 1) a data.frame or data.table of files and metadata, and 2) a list of optional arguments to pass to an import function.
outputs: A list of length 2 containing: 1) a data.frame or data.table of files and metadata, and 2) a list of optional arguments to pass to an export function.
paths: Named list of modulePath, inputPath, and outputPath paths. Partial matching is performed.
.envir: Environment referencing the objects used in the simulation. Several "shortcuts" to accessing objects referenced by this environment are provided, and can be used on the simList object directly instead of specifying the .envir slot: $, [[, ls, ls.str, objs. See examples.

Accessor Methods

Several slot (and sub-slot) accessor methods are provided for use, and categorized into separate help pages:

simList-accessors-envir

Simulation enviroment.

simList-accessors-events

Scheduled and completed events.

simList-accessors-inout

Passing data in to / out of simulations.

simList-accessors-modules

Modules loaded and used; module dependencies.

simList-accessors-objects

Accessing objects used in the simulation.

simList-accessors-params

Global and module-specific parameters.

simList-accessors-paths

File paths for modules, inputs, and outputs.

simList-accessors-times

Simulation times.

Event Lists

Event lists are sorted (keyed) first by time, second by priority. Each event is represented by a data.table row consisting of:

eventTime

The time the event is to occur.

moduleName

The module from which the event is taken.

eventType

A character string for the programmer-defined event type.

eventPriority

The priority given to the event.

Details

Based on code from chapter 7.8.3 of Matloff (2011): "Discrete event simulation". Here, we implement a discrete event simulation in a more modular fashion so it's easier to add simulation components (i.e., "simulation modules"). We use S4 classes and methods, and use data.table instead of data.frame to implement the event queue (because it is much more efficient).

References

Matloff, N. (2011). The Art of R Programming (ch. 7.8.3). San Fransisco, CA: No Starch Press, Inc.. Retrieved from https://www.nostarch.com/artofr.htm