Using get_attribute inside branch

[Arash-72]

I have the following code in which some patients will need to see the nurse (which is determined by "nurse_lgl" column in df). However, I get the Error: "there is no arrival running"

set.seed(100)

patient <- trajectory() %>%
  seize("room", 1) %>% 
  branch( function() {get_attribute(env, "nurse_lgl")}, continue = c(TRUE),
          trajectory() %>% 
          seize("nurse", 1) %>%
          timeout_from_attribute("nursee") %>%
          release("nurse", 1) 
  ) %>%
  seize("doctor", 1) %>%
  timeout_from_attribute("doctor") %>%
  release("doctor", 1) %>%
  release("room", 1)

n <- 5 # number of patients
df <- data.frame(
  time = rexp(n, 1/10), 
  nursee = rgamma(n, 2, 2),
  doctor = rgamma(n, 5, 3),
  nurse_lgl = sample(c(TRUE,FALSE),n, replace = T)
) %>% mutate(time = cumsum(time))

env <- simmer() %>%
  add_resource("room", 10) %>%
  add_resource("nurse", 1) %>%
  add_resource("doctor", 1) %>%
  add_dataframe("patient", patient, df, time=c("absolute")) %>%
  run()

Thank you so much for your time and help in advance.

[Enchufa2]

If you are using the env in a trajectory, it is a good practice to define it in the first place to avoid referencing a non-existing object, or worse, a previous simulation (see this section of the vignettes). For example:

library(simmer)
set.seed(100)

env <- simmer()

patient <- trajectory() %>%
  seize("room", 1) %>% 
  branch( function() {get_attribute(env, "nurse_lgl")}, continue = c(TRUE),
          trajectory() %>% 
            seize("nurse", 1) %>%
            timeout_from_attribute("nursee") %>%
            release("nurse", 1) 
  ) %>%
  seize("doctor", 1) %>%
  timeout_from_attribute("doctor") %>%
  release("doctor", 1) %>%
  release("room", 1)

n <- 5 # number of patients
df <- data.frame(
  time = cumsum(rexp(n, 1/10)), 
  nursee = rgamma(n, 2, 2),
  doctor = rgamma(n, 5, 3),
  nurse_lgl = sample(c(TRUE,FALSE),n, replace = T)
)

env %>%
  add_resource("room", 10) %>%
  add_resource("nurse", 1) %>%
  add_resource("doctor", 1) %>%
  add_dataframe("patient", patient, df, time=c("absolute")) %>%
  run()

[Arash-72]

I see now.
Thank you so much.

[Arash-72]

I really appreciate it if you could also help me with one more question about get_attribute. In my simulation using now(env) I want to track events for each patient. But I can't used get_attribute for that purpose. Here is my code:

library(simmer)
set.seed(100)

env <- simmer()

patient <- trajectory() %>%
  seize("room", 1) %>% 
  branch( function() {get_attribute(env, "nurse_lgl")}, continue = c(TRUE),
          trajectory() %>% 
            seize("nurse", 1) %>%
            timeout_from_attribute("nursee") %>%
            release("nurse", 1) 
  ) %>%
  seize("doctor", 1) %>%
  set_attribute(paste0("patient_Meet_Doctor_start_",function() {get_attribute(env, "type_of_visit")}), function() {now(env)}) %>%
  timeout_from_attribute("doctor") %>%
  set_attribute(paste0("patient_Meet_Doctor_end_",function() {get_attribute(env, "type_of_visit")}), function() {now(env)}) %>%
  release("doctor", 1) %>%
  release("room", 1)

n <- 5 # number of patients
df <- data.frame(
  type_of_visit = c("A", "B", "B", "B", "A"),
  time = cumsum(rexp(n, 1/10)), 
  nursee = rgamma(n, 2, 2),
  doctor = rgamma(n, 5, 3),
  nurse_lgl = sample(c(TRUE,FALSE),n, replace = T)
)

env %>%
  add_resource("room", 10) %>%
  add_resource("nurse", 1) %>%
  add_resource("doctor", 1) %>%
  add_dataframe("patient", patient, df, time=c("absolute")) %>%
  run()

Thank you so much in advance.

[Enchufa2]

Sure. Two things:

1. You'll see an error in the code above: Error: add_dataframe: column 'type_of_visit' is not numeric. simmer does not support other than numeric attributes, so you'll need to input 1, 2, 3... instead of A, B, C..., and then make the conversion later if you need it.
2. With mon=2, attributes are automatically recorded, and whenever an arrival enters or leaves a resource is automatically recorded for you too anyway, so you don't really need to set those attributes.

Example:

library(simmer)
set.seed(100)

env <- simmer()

patient <- trajectory() %>%
  seize("room", 1) %>% 
  branch( function() {get_attribute(env, "nurse_lgl")}, continue = c(TRUE),
          trajectory() %>% 
            seize("nurse", 1) %>%
            timeout_from_attribute("nursee") %>%
            release("nurse", 1) 
  ) %>%
  seize("doctor", 1) %>%
  timeout_from_attribute("doctor") %>%
  release("doctor", 1) %>%
  release("room", 1)

n <- 5 # number of patients
df <- data.frame(
  type_of_visit = c(1, 2, 2, 2, 1),
  time = cumsum(rexp(n, 1/10)), 
  nursee = rgamma(n, 2, 2),
  doctor = rgamma(n, 5, 3),
  nurse_lgl = sample(c(TRUE,FALSE),n, replace = T)
)

env %>%
  add_resource("room", 10) %>%
  add_resource("nurse", 1) %>%
  add_resource("doctor", 1) %>%
  add_dataframe("patient", patient, df, time=c("absolute"), mon=2) %>%
  run()
#> simmer environment: anonymous | now: 55.8606610390023 | next: 
#> { Monitor: in memory }
#> { Resource: room | monitored: TRUE | server status: 0(10) | queue status: 0(Inf) }
#> { Resource: nurse | monitored: TRUE | server status: 0(1) | queue status: 0(Inf) }
#> { Resource: doctor | monitored: TRUE | server status: 0(1) | queue status: 0(Inf) }
#> { Source: patient | monitored: 2 | n_generated: 5 }

get_mon_arrivals(env, per_resource = TRUE)
#>        name start_time end_time activity_time resource replication
#> 1  patient0   9.242116 10.80635      1.564232   doctor           1
#> 2  patient0   9.242116 10.80635      1.564232     room           1
#> 3  patient1  16.480488 18.04934      1.568849   doctor           1
#> 4  patient1  16.480488 18.04934      1.568849     room           1
#> 5  patient2  17.526937 19.41015      1.360811   doctor           1
#> 6  patient2  17.526937 19.41015      1.360811     room           1
#> 7  patient3  48.500560 50.95533      2.454768   doctor           1
#> 8  patient3  48.500560 50.95533      2.454768     room           1
#> 9  patient4  54.748612 55.86066      1.112049   doctor           1
#> 10 patient4  54.748612 55.86066      1.112049     room           1
get_mon_attributes(env)
#>    time     name           key     value replication
#> 1     0 patient0 type_of_visit 1.0000000           1
#> 2     0 patient0        nursee 0.5609975           1
#> 3     0 patient0        doctor 1.5642324           1
#> 4     0 patient0     nurse_lgl 0.0000000           1
#> 5     0 patient1 type_of_visit 2.0000000           1
#> 6     0 patient1        nursee 0.9578109           1
#> 7     0 patient1        doctor 1.5688487           1
#> 8     0 patient1     nurse_lgl 0.0000000           1
#> 9     0 patient2 type_of_visit 2.0000000           1
#> 10    0 patient2        nursee 0.4360375           1
#> 11    0 patient2        doctor 1.3608113           1
#> 12    0 patient2     nurse_lgl 0.0000000           1
#> 13    0 patient3 type_of_visit 2.0000000           1
#> 14    0 patient3        nursee 1.0416319           1
#> 15    0 patient3        doctor 2.4547678           1
#> 16    0 patient3     nurse_lgl 0.0000000           1
#> 17    0 patient4 type_of_visit 1.0000000           1
#> 18    0 patient4        nursee 0.5430941           1
#> 19    0 patient4        doctor 1.1120486           1
#> 20    0 patient4     nurse_lgl 0.0000000           1

[Arash-72]

Got it!
Thank you so much.