Troubleshooting an error message "csvfiles does not contain any CSV files name"- rethinking::ulam()

Modeling
,
1

Hello:

I have been pondering about running a simple interaction between two categorical variables using rethinking::ulam() function for measuring weight changes between two treatments (treatment vs. control). Time points are recorded as factor type.

The fit function is quite simple using nlme package

lme(bmi~ trmt*time_pts+bmi_baseline,
                random = ~1|ID,
                  data=df.long, 
                na.action = na.omit)

Translating this simple linear mixed effect model to rethinking::ulam(), I wrote the following code:

dat<- list(
  B=df.long$bmi,
  bm=df.long$bmi_baseline,
  T=df.long$ID,
  P=case_when(df.long$time_pts ==1 ~1L,
              df.long$time_pts ==2 ~2L, 
              df.long$time_pts ==3 ~3L,),
  G= ifelse(df.long$trmt == 1, 1L, 2L)
)

fit.stan1<- ulam(
  alist(
    B ~ normal(mu, sigma),
    mu <- a+ b[P,G]+ bm*bm +c[T],     
    a ~ dnorm(33, 5),
    bm~dnorm(0,5),
    sigma~ dexp(1),

    #adaptive prior
    matrix[P,G]:b ~ dnorm(0,sigma_a),
    c[IDf] ~ normal (bbar, sigma_bar),

    #hyper-priors
    sigma_a ~ dexp(1),
    bbar ~ normal (0,5),
    sigma_bar ~ dexp(1)
  ),
  data=dat,
  seed=2022, 
  chains = 2,
  iter = 2000, 
  warmup = 1000
)

I believe I specified the model correctly, but it shows the following error message:

Warning: No chains finished successfully. Unable to retrieve the fit.Error in Stan::read_stan_csv(cmdstanfit$output_files()) : csvfiles does not contain any CSV file name

I am not sure what that error message is and how to trouble shoot it.
Any guidance on this matter would be greatly appreciated.

2

That means that there was an error in either the initialisation or estimation process - which could be an issue with either your data or your model. You’ll have to ask the ulam developers for guidance on how to get more information about the fitting/sampling if it isn’t being printed. Their github is here: GitHub - rmcelreath/rethinking: Statistical Rethinking course and book package

3

Thanks for your response!
Although I do not know exactly what happened, I was able to make the model run by replacing ID numbers (T=df.long$ID) to index ID ( T=1:nrow(df.long))). Leaving this message here just in case someone faces a similar problem and seeking STAN forum for a troubleshooting.