Event {ABM}

R6 class to create and represent an event

Description

R6 class to create and represent an event

R6 class to create and represent an event

Active bindings

time

returns the event time

get

returns the external pointer, which can then be passed to functions such as schedule and unschedule.

Methods

Public methods

• Event$new()

• Event$clone()

Method new()

Usage

Event$new(time, handler)

Arguments

time

the time that this event will occur. A length-1 numeric vector.

handler

an R function that handles the event when it occurs.

Details

The R handler function should take exactly 3 arguments

1. time: the current time in the simulation

2. sim: the simulation object, an external pointer

3. agent: the agent to whom this event is attached to.

The return value of the handler function is ignored.

Method clone()

The objects of this class are cloneable with this method.

Usage

Event$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

# This handler prints increases a counter in the state of the 
# Simulation object, and schedule another event every 0.1 time unit.
handler = function(time, sim, agent) {
  x = getState(sim)
  x$counter = x$counter + 1
  setState(sim, x)
  schedule(agent, newEvent(time + 0.1, handler))
}
# create a new simulation with no agents. but the simulation itself is
# an agent. So we can use all the methods of agent
sim = Simulation$new()
# set the state of the simulation, initialize the counter
sim$state = list(counter = 0)
# schedule a new event at time 0
sim$schedule(Event$new(0, handler))
# add a logger for the counter. Note that, because sim is an R6 class
# to use it in the newStateLogger function, we need to access the 
# external pointer using its $get method
sim$addLogger(newStateLogger("counter", sim$get, "counter"))
# run the simulation for 10 time units.
print(sim$run(0:10))
# interestingly, the counts are not exactly in 10 event time unit. 
# Firstly, report always happen before event, so event at time 0 is 
# not counted in the time interval 0 to 1. Secondly, the event time 
# is stored as a numeric value with increments of 0.1, which is 
# subject to rounding errors. So some the the integer tiome events
# may be before the reporting and some may be after.