Size of a draws object

ndraws() counts the post-warmup draws (all chains pooled), niterations() the draws per chain, nchains() the chains and nvariables() the sampled parameters. The names and meanings are posterior's; frmtmb registers methods with posterior so that the generics work whether or not that package is attached.

Usage

# S3 method for class 'frmtmb_draws'
ndraws(x)

# S3 method for class 'frmtmb_draws'
nchains(x)

# S3 method for class 'frmtmb_draws'
niterations(x)

# S3 method for class 'frmtmb_draws'
nvariables(x, ...)

Arguments

x

A frmtmb_draws from frm_sample().

...

Unused. nvariables() carries it because posterior's generic does.

Value

A single integer.

Examples

# \donttest{
if (requireNamespace("tmbstan", quietly = TRUE) &&
    requireNamespace("rstan", quietly = TRUE) &&
    !frmtmb.sample:::tmbstan_build_broken()) {
  set.seed(9)
  dd <- data.frame(x = rnorm(60), g = factor(rep(1:6, 10)))
  dd$y <- rnorm(60, 1 + 0.5 * dd$x + rnorm(6, 0, 0.5)[dd$g], 1)
  ds <- frm_sample(bf(y ~ x + (1 | g)), family = gaussian(),
                   data = dd, chains = 1, iter = 500, refresh = 0)
  c(ndraws(ds), niterations(ds), nchains(ds), nvariables(ds))
}
#> frm_sample(): default priors (brms 2.23 defaults; prior = "flat" puts brms's (flat) in every slot)
#>   Intercept          student_t(3, 0.8, 2.5)
#>   sigma              student_t(3, 0, 2.5)  [natural scale]
#>   sd                 student_t(3, 0, 2.5)  [natural sd scale]
#>   b                  (flat), as brms leaves slopes
#> Warning: The largest R-hat is 1.08, indicating chains have not mixed.
#> Running the chains for more iterations may help. See
#> https://mc-stan.org/misc/warnings.html#r-hat
#> Warning: Bulk Effective Samples Size (ESS) is too low, indicating posterior means and medians may be unreliable.
#> Running the chains for more iterations may help. See
#> https://mc-stan.org/misc/warnings.html#bulk-ess
#> Warning: Tail Effective Samples Size (ESS) is too low, indicating posterior variances and tail quantiles may be unreliable.
#> Running the chains for more iterations may help. See
#> https://mc-stan.org/misc/warnings.html#tail-ess
#> [1] 250 250   1  12
# }