queueTrace {simEd}

Trace Data for Single-Server Queue Simulation

Description

This data set contains the arrival and service times for 1000 jobs arriving to a generic single-server queue.

Usage

queueTrace

Format

A list of two vectors, arrivalTimes and serviceTimes.

Details

This trace data could be used as input for the ssq function, but not directly. That is, ssq expects interarrival and service functions as input, not vectors of arrival times and service times. Accordingly, the user will need to write functions to extract the interarrival and service times from this trace, which can then be passed to ssq. See examples below.

Source

Discrete-Event Simulation: A First Course (2006). L.M. Leemis and S.K. Park. Pearson/Prentice Hall, Upper Saddle River, NJ. ISBN-13: 978-0131429178

Examples

interarrivalTimes   <- c(queueTrace$arrivalTimes[1], diff(queueTrace$arrivalTimes))
serviceTimes        <- queueTrace$serviceTimes

avgInterarrivalTime <- mean(interarrivalTimes)
avgServiceTime      <- mean(serviceTimes)

# functions to use this trace data for the ssq() function;
# note that the functions below destroy the global values of the copied
# interarrivalTimes and serviceTimes vectors along the way...
#
interarrivalTimes <- NULL
serviceTimes      <- NULL
getInterarr <- function(...)
{
   if (length(interarrivalTimes) == 0) {
          interarrivalTimes <- c(queueTrace$arrivalTimes[1],
                                  diff(queueTrace$arrivalTimes))
    }
    nextInterarr <- interarrivalTimes[1]
    interarrivalTimes <- interarrivalTimes[-1]
    return(nextInterarr)
}
getService <- function(...)
{
    if (length(serviceTimes) == 0) {
        serviceTimes <- queueTrace$serviceTimes
    }
    nextService <- serviceTimes[1]
    serviceTimes <- serviceTimes[-1] 
    return(nextService)
}
ssq(maxArrivals = 1000, interarrivalFcn = getInterarr, serviceFcn = getService)