function for rethinking style posterior list

NAMESPACE

@@ -5,6 +5,7 @@ S3method(print,coevsummary)
 S3method(summary,coevfit)
 export(coev_calculate_delta_theta)
 export(coev_calculate_theta)
+export(coev_extract_samples)
 export(coev_fit)
 export(coev_make_stancode)
 export(coev_make_standata)

R/coev_extract_samples.R

@@ -0,0 +1,32 @@
+#' Extract samples (draws) from a fitted \code{coevfit} object
+#'
+#' @param object An object of class \code{coevfit}
+#'
+#' @return Samples in 'rethinking' style list format
+#' @export
+#' 
+coev_extract_samples <- function(object) {
+  # stop if object is not of class coevfit
+  if (!methods::is(object, "coevfit")) {
+    stop2(
+      paste0(
+        "Argument 'object' must be a fitted coevolutionary model ",
+        "of class coevfit."
+        )
+      )
+  }
+  # stop if rethinking package not installed
+  if (!requireNamespace("rethinking", quietly = TRUE)) {
+    stop2(
+      paste0(
+        "'rethinking' package must be installed to use this function. See https://github.com/rmcelreath/rethinking"
+        )
+      )
+  }
+    vars <- object$fit$metadata()$stan_variables
+    draws <- posterior::as_draws_rvars(object$fit$draws())
+
+    return(lapply(vars, \(var_name){  
+      posterior::draws_of(draws[[var_name]], with_chains = FALSE)
+    }) |> setNames(vars))
+}