R Simmer - 使用 set_attribute 和 get_attribute 和复制（使用 lapply）

Question

我正在尝试结合 set_attribute 和 get_attribute 复制（使用 lapply） 以下没有“get_attribute”的代码运行良好：

library(simmer)    

SystemTime <- 200
delay= c(20,40,60,80,100,120,140,160,180,200)/60
set.seed(1234)

elevators <- simmer()

worker <-
  trajectory("elevators service") %>% #trajectory name
  log_("new worker arrived") %>% #
  set_attribute("start_time", function() {now(elevators)}) %>%
  seize("elevator",amount = 1) %>% #elevator queue and service 
  timeout(function() sample(delay,1)) %>%
  release("elevator") 


elevators <-lapply(1:100, function(i) {
  simmer("elevators") %>%
  add_generator("worker", worker, function() exp(2)) %>% 
    add_resource("elevator",capacity = 2) %>% 
  run(until = SystemTime)

})

当我像下面这样添加“get_attribute”时：

library(simmer) 

SystemTime <- 200
delay= c(20,40,60,80,100,120,140,160,180,200)/60
set.seed(1234)

elevators <- simmer()

worker <-
  trajectory("elevators service") %>% #trajectory name
  log_("new worker arrived") %>% #
  set_attribute("start_time", function() {now(elevators)}) %>%
  seize("elevator",amount = 1) %>% #elevator queue and service 
  timeout(function() sample(delay,1)) %>%
  log_(function() {paste("Waited: ", now(elevators) - get_attribute(elevators, "start_time"))}) %>%
  release("elevator") 


elevators <-lapply(1:100, function(i) {
  simmer("elevators") %>%
  add_generator("worker", worker, function() exp(2)) %>% 
    add_resource("elevator",capacity = 2) %>% 
  run(until = SystemTime)

})

我收到以下错误：

run_(private$sim_obj, until) 中的错误：评估错误：存在 没有到达运行。

寻求有关如何解决此问题的帮助？

Answer 1

您的第一个示例运行没有错误，但实际上运行不佳。基本上，你有一个范围问题。模拟环境必须在轨迹范围内，这样get_attribute（和now）才能看到。解决方案是将所有内容放在同一个函数中：

library(simmer) 

SystemTime <- 200
delay= c(20,40,60,80,100,120,140,160,180,200)/60
set.seed(1234)

elevators <-lapply(1:100, function(i) {
  elevator <- simmer("elevator")

  worker <-
    trajectory("elevator service") %>% #trajectory name
    log_("new worker arrived") %>% #
    set_attribute("start_time", function() {now(elevator)}) %>%
    seize("elevator",amount = 1) %>% #elevator queue and service 
    timeout(function() sample(delay,1)) %>%
    log_(function() {paste("Waited: ", now(elevator) - get_attribute(elevator, "start_time"))}) %>%
    release("elevator") 

  elevator %>%
    add_generator("worker", worker, function() rexp(1, 2)) %>% 
    add_resource("elevator", capacity = 2) %>% 
    run(until = SystemTime)
})

另请注意，我在您的生成器中将 exp(2) 替换为 rexp(1, 2)，我认为这是您真正想要的。