Implement set_proposal_fun

Author: apulsipher

Diff for: src/lfmcmc.cpp

@@ -72,7 +72,28 @@ SEXP set_proposal_fun_cpp(
     cpp11::function fun
 ) {
 
-    cpp11::stop("Un implemented");
+    LFMCMCProposalFun<TData_default> fun_call = [fun](
+        std::vector< epiworld_double >& params_now,
+        const std::vector< epiworld_double >& params_prev,
+        LFMCMC<TData_default>*
+        ) -> void {
+
+        auto params_doubles = cpp11::doubles(params_prev);
+
+        auto res_tmp = cpp11::doubles(fun(params_doubles));
+
+        std::copy(
+            res_tmp.begin(),
+            res_tmp.end(),
+            params_now.begin()
+            );
+
+        return;
+    };
+
+    WrapLFMCMC(lfmcmc_ptr)(lfmcmc);
+
+    lfmcmc_ptr->set_proposal_fun(fun_call);
 
     return lfmcmc;
 }

Diff for: vignettes/likelihood-free-mcmc.Rmd

@@ -80,6 +80,12 @@ sumfun <- function(dat) {
   return(dat)
 }
 
+# Define the LFMCMC proposal function
+propfun <- function(params_prev) {
+  res <- params_prev + rnorm(length(params_prev), )
+  return(res)
+}
+
 # Define the LFMCMC kernel function
 # - Based on kernel_fun_uniform from lfmcmc-meat.hpp
 kernelfun <- function(stats_now, stats_obs, epsilon) {
@@ -95,7 +101,7 @@ kernelfun <- function(stats_now, stats_obs, epsilon) {
 lfmcmc_model <- LFMCMC(model_sir) |>
   set_simulation_fun(simfun) |>
   set_summary_fun(sumfun) |>
-  use_proposal_norm_reflective() |>
+  set_proposal_fun(propfun) |>
   set_kernel_fun(kernelfun) |>
   set_observed_data(obs_data)
 ```