add 'nsamples' generic

NAMESPACE

@@ -13,6 +13,7 @@ export(loo_linpred)
 export(loo_pit)
 export(loo_predict)
 export(loo_predictive_interval)
+export(nsamples)
 export(posterior_interval)
 export(posterior_linpred)
 export(posterior_predict)

R/nsamples.R

@@ -0,0 +1,21 @@
+#' Generic function for extracting the number of posterior samples
+#'
+#' Extract the number of posterior samples stored in a fitted Bayesian model.
+#'
+#' @export
+#' @template args-object
+#' @template args-dots
+#'
+#' @examples
+#' # Example using rstanarm package:
+#' # nsamples method for 'stanreg' objects
+#' \donttest{
+#' if (require("rstanarm")) {
+#'   fit <- stan_glm(mpg ~ wt + am, data = mtcars)
+#'   nsamples(fit)
+#' }
+#' }
+#'
+nsamples <- function(object, ...) {
+  UseMethod("nsamples")
+}