use better ess in neff_ratio

NAMESPACE

@@ -608,7 +608,6 @@ importFrom(bayesplot,log_posterior)
 importFrom(bayesplot,neff_ratio)
 importFrom(bayesplot,nuts_params)
 importFrom(bayesplot,pp_check)
-importFrom(bayesplot,rhat)
 importFrom(bayesplot,theme_default)
 importFrom(bridgesampling,bayes_factor)
 importFrom(bridgesampling,bridge_sampler)
@@ -640,6 +639,7 @@ importFrom(posterior,nchains)
 importFrom(posterior,ndraws)
 importFrom(posterior,niterations)
 importFrom(posterior,nvariables)
+importFrom(posterior,rhat)
 importFrom(posterior,subset_draws)
 importFrom(posterior,summarize_draws)
 importFrom(posterior,variables)

R/diagnostics.R

@@ -54,15 +54,15 @@ nuts_params.brmsfit <- function(object, pars = NULL, ...) {
 }
 
 #' @rdname diagnostic-quantities
-#' @importFrom bayesplot rhat
+#' @importFrom posterior rhat
 #' @export rhat
 #' @export
 rhat.brmsfit <- function(object, pars = NULL, ...) {
   contains_draws(object)
   # bayesplot uses outdated rhat code from rstan
   # bayesplot::rhat(object$fit, pars = pars, ...)
   draws <- as_draws_array(object, variable = pars, ...)
-  tmp <- posterior::summarize_draws(draws, rhat = posterior::rhat)
+  tmp <- posterior::summarise_draws(draws, rhat = posterior::rhat)
   rhat <- tmp$rhat
   names(rhat) <- tmp$variable
   rhat
@@ -77,9 +77,11 @@ neff_ratio.brmsfit <- function(object, pars = NULL, ...) {
   # bayesplot uses outdated ess code from rstan
   # bayesplot::neff_ratio(object$fit, pars = pars, ...)
   draws <- as_draws_array(object, variable = pars, ...)
-  # currently uses ess_bulk as ess estimate for the central tendency
-  tmp <- posterior::summarize_draws(draws, ess = posterior::ess_bulk)
-  ess <- tmp$ess
+  tmp <- posterior::summarise_draws(
+    draws, ess_bulk = posterior::ess_bulk, ess_tail = posterior::ess_tail
+  )
+  # min of ess_bulk and ess_tail mimics definition of posterior::rhat.default
+  ess <- matrixStats::rowMins(cbind(tmp$ess_bulk, tmp$ess_tail))
   names(ess) <- tmp$variable
   ess / ndraws(draws)
 }