Assembles a fitted model's posterior draws into an [iteration, chain, parameter] array – the layout expected by bayesplot and analogous to
posterior::as_draws_array(). Multiple chains are recognised from a 3D
draws array, a $chain_id row map, or an $n_chains count over chain-major
rows; a single pooled chain yields a one-chain array.
Value
A numeric array with dimensions [n_iter, n_chain, n_param] and the
parameter names on the third dimension, or NULL if the fit carries no
draws. Chains of unequal length are truncated to the shortest.
Details
As with posterior_sample(), a fit that carries no draws returns NULL with
a message naming its backend and the representation it carries instead.