Please find below a short explanation of the most important terminologies used in the docs.
Arrival An arrival is created by a generator. An arrival can be considered a process, an active entity which has a number of activities associated to it and (in general) a limited lifetime in the system. These activities conform to a trajectory specification.
Trajectory When a generator creates an arrival, it couples the arrival to a given trajectory. A trajectory is defined as an interlinkage of activities which together form the arrivals’ lifetime in the system. Once an arrival is coupled to the trajectory, it will (in general) start processing the activities in the trajectory in the specified order and, eventually, leave the system.
Activity There are different kinds of activities that allow arrivals to interact with resources, perform custom tasks while spending time in the system, move back and forth through the trajectory dynamically… Currently, the set of available activities consist of
branch. See their respective documentation for details (e.g.
Generator A generator is a process which creates arrivals with a given interarrival time pattern. These arrivals follow a specified trajectory.
In the simulation model below we create a trajectory which we will call
my trajectory. This trajectory consists of three consecutive activities; a
release event. In the
release events a associated resource type is specified. In this case the resource type is called
library(simmer) # create a trajectory "my_trajectory" # this trajectory consists of 3 activities, a seize, timeout and release activity. t0<- trajectory("my_trajectory") %>% # seize one unit of the resource called "operator" seize("operator", 1) %>% # spend some (stochastic) time holding that resource timeout(function() rpois(1,50)) %>% # release the previously seized unit of "operator" release("operator", 1)
Once the trajectory has been created, the simulation object (a
simmer instance) is set up. One of the first steps is to actually attach a resource instance called
operator. Next, a generator instance is attached. This generator, called
my_generator, has an associated trajectory (
my_trajectory stored in
t0) and an associated
dist function. Once
run() is called the simulation model will start running. The generator
my_generator will create an arrival at an interarrival time delivered by the function passed to
env<-simmer() %>% # a resource called "operator"" is created with a capacity of 1 and an infinite queue size add_resource("operator", 1, Inf) %>% # this generator will create arrivals at each interval rpois(1,40) during # the simulation lifetime (while "dist" returns positive time values) # the arrivals will follow the trajectory specified in t0 add_generator("my_generator", trajectory = t0, dist = function() rpois(1, 40)) %>% run()
For more information, see the other vignettes or the function specific help documentation (e.g.