adds feature to make inits from fit and draws objects

DESCRIPTION

@@ -29,7 +29,7 @@ URL: https://mc-stan.org/cmdstanr/, https://discourse.mc-stan.org
 BugReports: https://github.com/stan-dev/cmdstanr/issues
 Encoding: UTF-8
 LazyData: true
-RoxygenNote: 7.3.0
+RoxygenNote: 7.3.1
 Roxygen: list(markdown = TRUE, r6 = FALSE)
 SystemRequirements: CmdStan (https://mc-stan.org/users/interfaces/cmdstan)
 Depends:

R/args.R

@@ -77,11 +77,12 @@ CmdStanArgs <- R6::R6Class(
       }
       self$output_dir <- repair_path(self$output_dir)
       self$output_basename <- output_basename
-      if (is.function(init)) {
-        init <- process_init_function(init, length(self$proc_ids), model_variables)
-      } else if (is.list(init) && !is.data.frame(init)) {
-        init <- process_init_list(init, length(self$proc_ids), model_variables)
+      if (inherits(self$method_args, "PathfinderArgs")) {
+        num_inits <- self$method_args$num_paths
+      } else {
+        num_inits <- length(self$proc_ids)
       }
+      init <- process_init(init, num_inits, model_variables)
       self$init <- init
       self$opencl_ids <- opencl_ids
       self$num_threads = NULL
@@ -691,7 +692,12 @@ validate_cmdstan_args <- function(self) {
     assert_file_exists(self$data_file, access = "r")
   }
   num_procs <- length(self$proc_ids)
-  validate_init(self$init, num_procs)
+  if (inherits(self$method_args, "PathfinderArgs")) {
+    num_inits <- self$method_args$num_paths
+  } else {
+    num_inits <- length(self$proc_ids)
+  }
+  validate_init(self$init, num_inits)
   validate_seed(self$seed, num_procs)
   if (!is.null(self$opencl_ids)) {
     if (cmdstan_version() < "2.26") {
@@ -1018,17 +1024,63 @@ validate_exe_file <- function(exe_file) {
   invisible(TRUE)
 }
 
+
+#' Generic for processing inits
+#' @noRd
+process_init <- function(...) {
+  UseMethod("process_init")
+}
+
+#' Default method
+#' @noRd
+process_init.default <- function(x, ...) {
+  return(x)
+}
+
+#' Write initial values to files if provided as posterior `draws` object
+#' @noRd
+#' @param init A type that inherits the `posterior::draws` class.
+#' @param num_procs Number of inits requested
+#' @param model_variables  A list of all parameters with their types and
+#'   number of dimensions. Typically the output of model$variables().
+#' @param warn_partial Should a warning be thrown if inits are only specified
+#'   for a subset of parameters? Can be controlled by global option
+#'   `cmdstanr_warn_inits`.
+#' @return A character vector of file paths.
+process_init.draws <- function(init, num_procs, model_variables = NULL,
+                               warn_partial = getOption("cmdstanr_warn_inits", TRUE)) {
+  if (!is.null(model_variables)) {
+    variable_names = names(model_variables$parameters)
+  } else {
+    variable_names = colnames(draws)[!grepl("__", colnames(draws))]
+  }
+  draws <- posterior::subset_draws(init, variable = variable_names)
+  draws <- posterior::resample_draws(draws, ndraws = num_procs,
+                                     method ="simple_no_replace")
+  draws_rvar = posterior::as_draws_rvars(draws)
+  inits = lapply(1:num_procs, \(draw_iter) {
+    init_i = lapply(variable_names, \(var_name) {
+      x = drop(posterior::draws_of(drop(
+        posterior::subset_draws(draws_rvar[[var_name]], draw=draw_iter))))
+      return(x)
+    })
+    names(init_i) = variable_names
+    return(init_i)
+  })
+  return(process_init(inits, num_procs, model_variables, warn_partial))
+}
+
 #' Write initial values to files if provided as list of lists
 #' @noRd
 #' @param init List of init lists.
-#' @param num_procs Number of CmdStan processes.
+#' @param num_procs Number of inits needed.
 #' @param model_variables  A list of all parameters with their types and
 #'   number of dimensions. Typically the output of model$variables().
 #' @param warn_partial Should a warning be thrown if inits are only specified
 #'   for a subset of parameters? Can be controlled by global option
 #'   `cmdstanr_warn_inits`.
 #' @return A character vector of file paths.
-process_init_list <- function(init, num_procs, model_variables = NULL,
+process_init.list <- function(init, num_procs, model_variables = NULL,
                               warn_partial = getOption("cmdstanr_warn_inits", TRUE)) {
   if (!all(sapply(init, function(x) is.list(x) && !is.data.frame(x)))) {
     stop("If 'init' is a list it must be a list of lists.", call. = FALSE)
@@ -1083,10 +1135,11 @@ process_init_list <- function(init, num_procs, model_variables = NULL,
   }
   init_paths <-
     tempfile(
-      pattern = paste0("init-", seq_along(init), "-"),
+      pattern = "init-",
       tmpdir = cmdstan_tempdir(),
-      fileext = ".json"
+      fileext = ""
     )
+  init_paths <- paste0(init_paths, "_", seq_along(init), ".json")
   for (i in seq_along(init)) {
     write_stan_json(init[[i]], init_paths[i])
   }
@@ -1096,11 +1149,12 @@ process_init_list <- function(init, num_procs, model_variables = NULL,
 #' Write initial values to files if provided as function
 #' @noRd
 #' @param init Function generating a single list of initial values.
-#' @param num_procs Number of CmdStan processes.
+#' @param num_procs Number of inits needed.
 #' @param model_variables A list of all parameters with their types and
 #'   number of dimensions. Typically the output of model$variables().
 #' @return A character vector of file paths.
-process_init_function <- function(init, num_procs, model_variables = NULL) {
+process_init.function <- function(init, num_procs, model_variables = NULL,
+                                  warn_partial = getOption("cmdstanr_warn_inits", TRUE)) {
   args <- formals(init)
   if (is.null(args)) {
     fn_test <- init()
@@ -1116,7 +1170,159 @@ process_init_function <- function(init, num_procs, model_variables = NULL) {
   if (!is.list(fn_test) || is.data.frame(fn_test)) {
     stop("If 'init' is a function it must return a single list.")
   }
-  process_init_list(init_list, num_procs, model_variables)
+  process_init(init_list, num_procs, model_variables)
+}
+
+#' Write initial values to files if provided as a `CmdStanMCMC` class
+#' @noRd
+#' @param init A `CmdStanMCMC` class
+#' @param num_procs Number of inits requested
+#' @param model_variables  A list of all parameters with their types and
+#'   number of dimensions. Typically the output of model$variables().
+#' @param warn_partial Should a warning be thrown if inits are only specified
+#'   for a subset of parameters? Can be controlled by global option
+#'   `cmdstanr_warn_inits`.
+#' @return A character vector of file paths.
+process_init.CmdStanMCMC <- function(init, num_procs, model_variables = NULL,
+                                     warn_partial = getOption("cmdstanr_warn_inits", TRUE)) {
+  # Convert from data.table to data.frame
+  if (all(init$return_codes() == 1)) {
+    stop("We are unable to create initial values from a model with no samples. Please check the results of the model used for inits before continuing.")
+  } else if (!any(names(model_variables$parameters) %in% init$metadata()$stan_variables)) {
+    stop("None of the names of the parameters for the model used for initial values match the names of parameters from the model currently running.")
+  }
+  draws_df = init$draws(format = "df")
+  if (is.null(model_variables)) {
+    model_variables = list(parameters = colnames(draws_df)[2:(length(colnames(draws_df)) - 3)])
+  }
+  init_draws_df = posterior::resample_draws(draws_df, ndraws = num_procs,
+                                            method = "simple_no_replace")
+  init_draws_lst = process_init(init_draws_df,
+                                num_procs = num_procs, model_variables = model_variables)
+  return(init_draws_lst)
+}
+
+#' Performs PSIS resampling on the draws from an approxmation method for inits.
+#' @noRd
+#' @param init A set of draws with `lp__` and `lp_approx__` columns.
+#' @param num_procs Number of inits requested
+#' @param model_variables  A list of all parameters with their types and
+#'   number of dimensions. Typically the output of model$variables().
+#' @param warn_partial Should a warning be thrown if inits are only specified
+#'   for a subset of parameters? Can be controlled by global option
+#'   `cmdstanr_warn_inits`.
+#' @return A character vector of file paths.
+process_init_approx <- function(init, num_procs, model_variables = NULL,
+                                warn_partial = getOption("cmdstanr_warn_inits", TRUE)) {
+  # Convert from data.table to data.frame
+  if (init$return_codes() == 1) {
+    stop("We are unable to create initial values from a model with no samples. Please check the results of the model used for inits before continuing.")
+  } else if (!any(names(model_variables$parameters) %in% init$metadata()$stan_variables)) {
+    stop("None of the names of the parameters for the model used for initial values match the names of parameters from the model currently running.")
+  }
+  draws_df = init$draws(format = "df")
+  if (is.null(model_variables)) {
+    model_variables = list(parameters = colnames(draws_df)[3:(length(colnames(draws_df)) - 3)])
+  }
+  draws_df$lw = draws_df$lp__ - draws_df$lp_approx__
+  # Calculate unique draws based on 'lw' using base R functions
+  unique_draws = length(unique(draws_df$lw))
+  if (num_procs > unique_draws) {
+    if (inherits(init, "CmdStanPathfinder")) {
+      stop(paste0("Not enough distinct draws (", num_procs, ") in pathfinder fit to create inits. Try running Pathfinder with psis_resample=FALSE"))
+    } else {
+      stop(paste0("Not enough distinct draws (", num_procs, ") to create inits."))
+    }
+  }
+  if (unique_draws < (0.95 * nrow(draws_df))) {
+    temp_df = aggregate(.draw ~ lw, data = draws_df, FUN = min)
+    draws_df = posterior::as_draws_df(merge(temp_df, draws_df, by = 'lw'))
+    draws_df$pareto_weight = exp(draws_df$lw - max(draws_df$lw))
+  } else {
+    draws_df$pareto_weight = posterior::pareto_smooth(
+      exp(draws_df$lw - max(draws_df$lw)), tail = "right")[["x"]]
+  }
+  init_draws_df = posterior::resample_draws(draws_df, ndraws = num_procs,
+                                            weights = draws_df$pareto_weight, method = "simple_no_replace")
+  init_draws_lst = process_init(init_draws_df,
+                                num_procs = num_procs, model_variables = model_variables, warn_partial)
+  return(init_draws_lst)
+}
+
+
+#' Write initial values to files if provided as a `CmdStanPathfinder` class
+#' @noRd
+#' @param init A `CmdStanPathfinder` class
+#' @param num_procs Number of inits requested
+#' @param model_variables  A list of all parameters with their types and
+#'   number of dimensions. Typically the output of model$variables().
+#' @param warn_partial Should a warning be thrown if inits are only specified
+#'   for a subset of parameters? Can be controlled by global option
+#'   `cmdstanr_warn_inits`.
+#' @return A character vector of file paths.
+process_init.CmdStanPathfinder <- function(init, num_procs, model_variables = NULL,
+                                           warn_partial = getOption("cmdstanr_warn_inits", TRUE)) {
+  process_init_approx(init, num_procs, model_variables, warn_partial)
+}
+
+#' Write initial values to files if provided as a `CmdStanVB` class
+#' @noRd
+#' @param init A `CmdStanVB` class
+#' @param num_procs Number of inits requested
+#' @param model_variables  A list of all parameters with their types and
+#'   number of dimensions. Typically the output of model$variables().
+#' @param warn_partial Should a warning be thrown if inits are only specified
+#'   for a subset of parameters? Can be controlled by global option
+#'   `cmdstanr_warn_inits`.
+#' @return A character vector of file paths.
+process_init.CmdStanVB <- function(init, num_procs, model_variables = NULL,
+                                   warn_partial = getOption("cmdstanr_warn_inits", TRUE)) {
+  process_init_approx(init, num_procs, model_variables, warn_partial)
+}
+
+#' Write initial values to files if provided as a `CmdStanLaplace` class
+#' @noRd
+#' @param init A `CmdStanLaplace` class
+#' @param num_procs Number of inits requested
+#' @param model_variables  A list of all parameters with their types and
+#'   number of dimensions. Typically the output of model$variables().
+#' @param warn_partial Should a warning be thrown if inits are only specified
+#'   for a subset of parameters? Can be controlled by global option
+#'   `cmdstanr_warn_inits`.
+#' @return A character vector of file paths.
+process_init.CmdStanLaplace <- function(init, num_procs, model_variables = NULL,
+                                        warn_partial = getOption("cmdstanr_warn_inits", TRUE)) {
+  process_init_approx(init, num_procs, model_variables, warn_partial)
+}
+
+
+#' Write initial values to files if provided as a `CmdStanMLE` class
+#' @noRd
+#' @param init A `CmdStanMLE` class
+#' @param num_procs Number of inits requested
+#' @param model_variables  A list of all parameters with their types and
+#'   number of dimensions. Typically the output of model$variables().
+#' @param warn_partial Should a warning be thrown if inits are only specified
+#'   for a subset of parameters? Can be controlled by global option
+#'   `cmdstanr_warn_inits`.
+#' @return A character vector of file paths.
+process_init.CmdStanMLE <- function(init, num_procs, model_variables = NULL,
+                                    warn_partial = getOption("cmdstanr_warn_inits", TRUE)) {
+  # Convert from data.table to data.frame
+  if (init$return_codes() == 1) {
+    stop("We are unable to create initial values from a model with no samples. Please check the results of the model used for inits before continuing.")
+  } else if (!any(names(model_variables$parameters) %in% init$metadata()$stan_variables)) {
+    stop("None of the names of the parameters for the model used for initial values match the names of parameters from the model currently running.")
+  }
+  draws_df = init$draws(format = "df")
+  if (is.null(model_variables)) {
+    model_variables = list(parameters = colnames(draws_df)[2:(length(colnames(draws_df)) - 3)])
+  }
+  init_draws_df = posterior::resample_draws(draws_df, ndraws = num_procs,
+                                            method = "simple")
+  init_draws_lst_lst = process_init(init_draws_df,
+                                    num_procs = num_procs, model_variables = model_variables, warn_partial)
+  return(init_draws_lst_lst)
 }
 
 #' Validate initial values

R/cmdstanr-package.R

@@ -30,6 +30,6 @@
 #' @inherit cmdstan_model examples
 #' @import R6
 #'
-NULL
+"_PACKAGE"
 
 if (getRversion() >= "2.15.1")  utils::globalVariables(c("self", "private", "super"))

R/fit.R

@@ -518,11 +518,11 @@ unconstrain_variables <- function(variables) {
          " not provided!", call. = FALSE)
   }
 
-  # Remove zero-length parameters from model_variables, otherwise process_init_list
+  # Remove zero-length parameters from model_variables, otherwise process_init
   # warns about missing inputs
   model_variables$parameters <- model_variables$parameters[nonzero_length_params]
 
-  stan_pars <- process_init_list(list(variables), num_procs = 1, model_variables)
+  stan_pars <- process_init(list(variables), num_procs = 1, model_variables)
   private$model_methods_env_$unconstrain_variables(private$model_methods_env_$model_ptr_, stan_pars)
 }
 CmdStanFit$set("public", name = "unconstrain_variables", value = unconstrain_variables)
@@ -594,7 +594,7 @@ unconstrain_draws <- function(files = NULL, draws = NULL,
   # but not in metadata()$variables
   nonzero_length_params <- names(model_variables$parameters) %in% model_par_names
 
-  # Remove zero-length parameters from model_variables, otherwise process_init_list
+  # Remove zero-length parameters from model_variables, otherwise process_init
   # warns about missing inputs
   pars <- names(model_variables$parameters[nonzero_length_params])