对于Simmer库和R来说,我都是新手,所以我希望有人可以帮助我解决这个问题。
Simmer文档中的示例显示了一个重新库存监视器,该监视器按设定的时间间隔检查库存,但是我希望在客户检索到一定数量的库存后立即进行重新库存。我尝试创建一个不确定的开始时间的补货生成器,并使用set_source("Restock", at(now(env))
重新计划在当前模拟时间发生的补货,但这似乎行不通。有什么建议吗?
# Inv. properties
INV_CAP <- 100
INV_TRIG <- 30
INV_LEVEL <- INV_CAP
# Environment rates
SERVE_RATE <- 1/10
RESTOCK_RATE <- 1/10
env <- simmer()
restock <- trajectory() %>%
# Restock only beneath INV_TRIG threshold
branch(function() INV_LEVEL <= INV_TRIG,
continue = TRUE,
trajectory() %>%
log_("Begin restock") %>%
timeout(function() rexp(1, RESTOCK_RATE)) %>%
log_(function(){
INV_LEVEL <<- INV_CAP
paste("Restock finished")
}))
serve <- trajectory() %>%
log_("Begin serving") %>%
timeout(function() rexp(1, SERVE_RATE)) %>%
# Decrease inv. level and cust. demand
set_attribute("demand", function() {
amount <- min(INV_LEVEL, get_attribute(env, "demand"))
INV_LEVEL <<- INV_LEVEL - amount
return(-amount)
}, mod = "+")
customer <- trajectory() %>%
set_attribute("demand", function() sample(DEMAND_MIN:DEMAND_MAX, 1)) %>%
log_("Entering queue") %>%
seize("Server") %>%
join(serve) %>%
release("Server") %>%
log_("Finished")
env %>%
add_resource("Server", capacity = SERVER_CAP, queue_size = QUEUE_CAP) %>%
add_generator("Customer", customer, function() rexp(1, CUST_RATE), mon = 2) %>%
run(until = 500)
答案 0 :(得分:0)
要设置“重新库存”源,首先需要定义一个无效的“重新库存”生成器。考虑到它是不活动的,您需要在设置新源之后将其激活。我给你举个小例子:
library(simmer)
env <- simmer()
restock <- trajectory() %>%
log_("restock")
serve <- trajectory() %>%
log_("serve") %>%
set_source("Restock", at(0)) %>%
activate("Restock")
env %>%
add_generator("Customer", serve, at(1, 2, 3)) %>%
add_generator("Restock", restock, at(-1)) %>%
run()
编辑:如果定义以下便利功能(我想在下一个版本中将其添加到simmer
中)
when_activated <- function(n=1) {
first <- TRUE
function() {
if (first) {
first <<- FALSE
return(-1)
}
c(rep(0, n), -1)
}
}
然后
library(simmer)
env <- simmer()
restock <- trajectory() %>%
log_("restock")
serve <- trajectory() %>%
log_("serve") %>%
activate("Restock")
env %>%
add_generator("Customer", serve, at(1, 2, 3)) %>%
add_generator("Restock", restock, when_activated()) %>%
run()
就是这样。