Handle user-supplied posterior draws

Handle user-supplied posterior draws

Usage

# S3 method for class 'gamm4'
user_draws(model, ..., draws, n_draws = NULL, chains = NULL)

user_draws(model, ..., draws)

# S3 method for class 'gam'
user_draws(model, ..., n_draws = NULL, chains = NULL, draws, index = NULL)

# S3 method for class 'scam'
user_draws(
  model,
  ...,
  draws = NULL,
  n_draws = NULL,
  chains = NULL,
  index = NULL
)

Arguments

model

a fitted model from mgcv::gam(), mgcv::bam(), scam::scam(), or gamm4::gamm4(), or a model inheriting from these classes. See gamm4_support for sampling from gamm4 fits.

...

arguments passed to methods.

draws

matrix; user supplied posterior draws to be used when method = "user".

n_draws

positive integer; total retained draws across all chains. Required when generating draws. With method = "user", the supplied matrix determines the count; an explicit count must agree with its rows.

chains

positive integer or NULL; number of chains. NULL uses one chain, or the chain mapping in supplied draws. n_draws must be divisible by chains. Burn-in is applied separately to each MH chain.

index

a vector to index (subset) the columns of draws.

Details

The supplied draws must be a matrix (currently), with 1 column per model coefficient, and 1 row per posterior draw. The "gam" method has argument index, which can be used to subset (select) coefficients (columns) of draws. index can be any valid way of selecting (indexing) columns of a matrix. index is useful if you have a set of posterior draws for the entire model (say from mgcv::gam.mh()) and you wish to use those draws for an individual smooth, via smooth_samples().

For SCAM models, supplied draws must contain finite transformed coefficients in the order returned by coef(model). If column names are supplied they must match exactly. Entries identified by model$p.ident must be nonnegative. Draws returned with parametrized = FALSE cannot be supplied directly for prediction; transform them first.

See also

gamm4_support