added doubling threshold option

R/set_smc_options.R

@@ -5,6 +5,9 @@
 #'   particle
 #' @param max_particle_filters Maximum number of particle filters.
 #' @param resampling_threshold Effective sample size threshold for resampling
+#' @param doubling_threshold Threshold for particle filter doubling. If the
+#'   acceptance rate of the rejuvenation step falls below this threshold, the
+#'   number of particle filters is doubled. Defaults to 0.2.
 #' @param max_rejuvenation_steps Maximum number of rejuvenation steps. If the
 #'   number of unique particles has not exceeded half the number of particles
 #'   after this many steps, the rejuvenation is still stopped.
@@ -22,7 +25,8 @@
 #'
 set_smc_options <- function(
     n_particles = 1000, n_particle_filters = 50, max_particle_filters = 10000,
-    resampling_threshold = n_particles / 2, max_rejuvenation_steps = 20,
+    resampling_threshold = n_particles / 2, doubling_threshold = .2,
+    max_rejuvenation_steps = 20,
     metric = "footrule", resampler = "multinomial",
     latent_rank_proposal = "uniform", verbose = FALSE,
     trace = FALSE, trace_latent = FALSE) {

src/options.cpp

@@ -9,6 +9,7 @@ Options::Options(const Rcpp::List& input_options) :
   max_particle_filters {input_options["max_particle_filters"]},
   resampling_threshold{input_options["resampling_threshold"]},
   max_rejuvenation_steps{input_options["max_rejuvenation_steps"]},
+  doubling_threshold{input_options["doubling_threshold"]},
   verbose{input_options["verbose"]},
   trace{input_options["trace"]},
   trace_latent{input_options["trace_latent"]}{}

src/options.h

@@ -14,6 +14,7 @@ struct Options{
   unsigned int max_particle_filters;
   unsigned int resampling_threshold;
   unsigned int max_rejuvenation_steps;
+  const double doubling_threshold;
   const bool verbose;
   const bool trace;
   const bool trace_latent;

src/run_smc.cpp

@@ -91,7 +91,7 @@ Rcpp::List run_smc(
       double acceptance_rate = accepted / particle_vector.size() / iter;
       reporter.report_acceptance_rate(acceptance_rate);
 
-      if(acceptance_rate < 0.2 && options.n_particle_filters < options.max_particle_filters) {
+      if(acceptance_rate < options.doubling_threshold && options.n_particle_filters < options.max_particle_filters) {
         for(auto& p : particle_vector) {
           double log_Z_old = compute_log_Z(p.particle_filters, t);