From bb463076b27d6f574a43a5e01fc18adc1a6f5081 Mon Sep 17 00:00:00 2001
From: Gavin Simpson <ucfagls@gmail.com>
Date: Wed, 6 Mar 2024 17:26:23 +0100
Subject: [PATCH] the sampler functions can now take a seed

---
 R/samplers.R | 39 ++++++++++++++++++++++++++-------------
 1 file changed, 26 insertions(+), 13 deletions(-)

diff --git a/R/samplers.R b/R/samplers.R
index cbfff7dcd..407215aba 100644
--- a/R/samplers.R
+++ b/R/samplers.R
@@ -47,6 +47,8 @@
 #'   to singular.
 #' @param draws matrix; user supplied posterior draws to be used when
 #'   `method = "user"`.
+#' @param seed numeric; the random seed to use. If `NULL`, a random seed will
+#'   be generated without affecting the current state of R's RNG.
 #' @param ... arguments passed to methods.
 #'
 #' @export
@@ -56,27 +58,33 @@
 
 #' @export
 #' @rdname post_draws
+#' @importFrom withr with_seed with_preserve_seed
 `post_draws.default` <- function(
     model, n,
     method = c("gaussian", "mh", "inla", "user"), mu = NULL, sigma = NULL,
     n_cores = 1L, burnin = 1000, thin = 1, t_df = 40, rw_scale = 0.25,
     index = NULL, frequentist = FALSE, unconditional = FALSE,
-    parametrized = TRUE, mvn_method = c("mvnfast", "mgcv"), draws = NULL, ...) {
+    parametrized = TRUE, mvn_method = c("mvnfast", "mgcv"), draws = NULL,
+    seed = NULL, ...) {
+  if (is.null(seed)) {
+    seed <- with_preserve_seed(runif(1))
+  }
   # what posterior sampling are we using
   method <- match.arg(method)
   mvn_method <- match.arg(mvn_method)
   betas <- switch(method,
-    "gaussian" = gaussian_draws(
+    "gaussian" = with_seed(seed, gaussian_draws(
       model = model, n = n,
       n_cores = n_cores, index = index, frequentist = frequentist,
       unconditional = unconditional, parametrized = parametrized,
       mvn_method = mvn_method, ...
-    ),
-    "mh" = mh_draws(
+    )),
+    "mh" = with_seed(seed, mh_draws(
       n = n, model = model, burnin = burnin,
       thin = thin, t_df = t_df, rw_scale = rw_scale, index = index, ...
-    ),
-    "inla" = .NotYetImplemented(),
+    )),
+    "inla" = stop("'method = \"inla\"' is not yet implemented.",
+    call. = FALSE),
     "user" = user_draws(model = model, draws = draws, ...)
   )
   betas
@@ -91,25 +99,30 @@
 
 #' @export
 #' @rdname post_draws
+#' @importFrom withr with_seed with_preserve_seed
 `generate_draws.gam` <- function(
     model, n, method = c("gaussian", "mh", "inla"),
     mu = NULL, sigma = NULL, n_cores = 1L, burnin = 1000, thin = 1, t_df = 40,
     rw_scale = 0.25, index = NULL, frequentist = FALSE, unconditional = FALSE,
-    mvn_method = c("mvnfast", "mgcv"), ...) {
+    mvn_method = c("mvnfast", "mgcv"), seed = NULL, ...) {
+  if (is.null(seed)) {
+    seed <- with_preserve_seed(runif(1))
+  }
   # what posterior sampling are we using
   method <- match.arg(method)
   mvn_method <- match.arg(mvn_method)
   betas <- switch(method,
-    "gaussian" = gaussian_draws(
+    "gaussian" = with_seed(seed, gaussian_draws(
       model = model, n = n,
       n_cores = n_cores, index = index, frequentist = frequentist,
       unconditional = unconditional, mvn_method = mvn_method, ...
-    ),
-    "mh" = mh_draws(
+    )),
+    "mh" = with_seed(seed, mh_draws(
       n = n, model = model, burnin = burnin,
-      thin = thin, t_df = t_df, rw_scale = rw_scale, index = index
-    ),
-    "inla" = .NotYetImplemented()
+      thin = thin, t_df = t_df, rw_scale = rw_scale, index = index, ...
+    )),
+    "inla" = stop("'method = \"inla\"' is not yet implemented.",
+    call. = FALSE)
   )
   betas
 }