rxode2 unexpected simulation

[mattfidler]

library(rxode2)
#> rxode2 2.1.2 using 8 threads (see ?getRxThreads)
#>   no cache: create with `rxCreateCache()`
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union

# First fit with if statement to indicate diff IV/PO
modA <- function() {
  ini({
    tka <- 0.45; backTransform("exp") # Log Ka
    tcl <- -7     # Log Cl
    tv  <- -8     # Log V
    eta.ka ~ 0.6
    eta.cl ~ 0.3
    eta.v ~ 0.1
    prop.sd <- 0.7
  })
  model({
    if(ROUTE!=1) ka <- exp(tka + eta.ka)
    cl <- exp(tcl + eta.cl)
    v <- exp(tv + eta.v)
    d/dt(depot) = -ka * depot
    d/dt(center) = ka * depot - cl / v * center
    cp = center / v
    cp ~ prop(prop.sd)
  })
}

et <- et(amount.units='mg', time.units='hours') %>%
  et(dose=10) %>% et(seq(0,8,0.2)) %>% mutate(ROUTE=1)
sims <- rxSolve(modA,et)
#> ℹ parameter labels from comments will be replaced by 'label()'
#> Warning: some etas defaulted to non-mu referenced, possible parsing error: eta.ka
#> as a work-around try putting the mu-referenced expression on a simple line
#> using C compiler: ‘gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0’
plot(sims)
#> Warning: Removed 40 rows containing missing values (`geom_line()`).
#> `geom_line()`: Each group consists of only one observation.
#> ℹ Do you need to adjust the group aesthetic?

^{Created on 2024-02-12 with reprex v2.1.0}

[mattfidler]

@RichardHooijmaijers I believe this is expected behavior.

What happens is the values in the problem are initialized to NA; If they are not changed in the simulation then they would remain NA.

This means that all things related to ka if route == 1 would be NA as well.

I suppose a better model would be:

library(rxode2)
#> rxode2 2.1.2 using 8 threads (see ?getRxThreads)
#>   no cache: create with `rxCreateCache()`
library(dplyr)
#> 
#> Attaching package: 'dplyr'
#> The following objects are masked from 'package:stats':
#> 
#>     filter, lag
#> The following objects are masked from 'package:base':
#> 
#>     intersect, setdiff, setequal, union

# First fit with if statement to indicate diff IV/PO
modA <- function() {
  ini({
    tka <- 0.45; backTransform("exp") # Log Ka
    tcl <- -7     # Log Cl
    tv  <- -8     # Log V
    eta.ka ~ 0.6
    eta.cl ~ 0.3
    eta.v ~ 0.1
    prop.sd <- 0.7
  })
  model({
    ka <- 0
    if(ROUTE!=1) ka <- exp(tka + eta.ka)
    cl <- exp(tcl + eta.cl)
    v <- exp(tv + eta.v)
    d/dt(depot) = -ka * depot
    d/dt(center) = ka * depot - cl / v * center
    cp = center / v
    cp ~ prop(prop.sd)
  })
}

et <- et(amount.units='mg', time.units='hours') %>%
  et(dose=10) %>% et(seq(0,8,0.2)) %>% mutate(ROUTE=1)
sims <- rxSolve(modA,et)
#> ℹ parameter labels from comments will be replaced by 'label()'
#> Warning: some etas defaulted to non-mu referenced, possible parsing error: eta.ka
#> as a work-around try putting the mu-referenced expression on a simple line
#> using C compiler: ‘gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0’
plot(sims)

#note that a dose to the depot (that is turned off) doesn't make sense
#anyway, so consider dosing to the central compartment:

et <- et(amount.units='mg', time.units='hours') %>%
  et(dose=10, cmt="center") %>% et(seq(0,8,0.2)) %>% mutate(ROUTE=1)
sims <- rxSolve(modA,et)
#> ℹ parameter labels from comments will be replaced by 'label()'
#> Warning: some etas defaulted to non-mu referenced, possible parsing error: eta.ka
#> as a work-around try putting the mu-referenced expression on a simple line
#> using C compiler: ‘gcc (Ubuntu 11.4.0-1ubuntu1~22.04) 11.4.0’
plot(sims)

^{Created on 2024-02-12 with reprex v2.1.0}