Extract posterior draws from a DPMirt fit

Provides convenient access to posterior samples in matrix or long format.

Usage

dpmirt_draws(
  fit,
  vars = c("theta", "beta", "lambda", "delta"),
  format = c("matrix", "long"),
  use_rescaled = TRUE
)

Arguments

fit

A dpmirt_fit object.

vars

Character vector of variables to extract. Options: "theta", "beta", "lambda", "delta".

format

Character. Output format: "matrix" or "long".

use_rescaled

Reserved. Only TRUE is currently supported.

Value

If one variable is requested in matrix format, a matrix (n_retained_draws x N or n_retained_draws x I). If multiple variables are requested in matrix format, a named list of matrices. In long format, a data.frame stacking all requested variables and chain/draw metadata, including retained MCMC iteration labels after thin or thin2.

Details

This function provides direct access to the posterior MCMC samples stored in a dpmirt_fit object. The matrix format (default) is efficient for computation, while the long format is convenient for visualization with ggplot2 and includes chain metadata when available. Raw draw extraction (use_rescaled = FALSE) is reserved until the raw/rescaled draw schema is finalized.

See also

dpmirt, dpmirt_estimates

Other estimation: dpmirt_estimates(), dpmirt_rescale()

Examples

if (FALSE) { # \dontrun{
sim <- dpmirt_simulate(200, 20, model = "rasch", seed = 42)
fit <- dpmirt(sim$response, model = "rasch", prior = "normal",
              niter = 5000, nburnin = 1000, seed = 123)

# Extract theta draws as matrix (retained draws x N)
theta <- dpmirt_draws(fit, vars = "theta")
dim(theta)

# Extract beta draws in long format
beta_long <- dpmirt_draws(fit, vars = "beta", format = "long")
head(beta_long)
} # }