rcpp函数未在r包中导出

Question

当我尝试从R包中加载某些c ++函数时，会遇到一些麻烦。运行devtools::check()将产生>

> checking R code for possible problems ... NOTE
  postRiverComp: no visible binding for global variable
    ‘_thmc_postRiverComp’
  preFlopComp: no visible binding for global variable ‘_thmc_preFlopComp’
  preRiverComp: no visible binding for global variable
    ‘_thmc_preRiverComp’
  preTurnComp: no visible binding for global variable ‘_thmc_preTurnComp’
  rcpp_hello_world: no visible binding for global variable
    ‘_thmc_rcpp_hello_world’
  Undefined global functions or variables:
    _thmc_postRiverComp _thmc_preFlopComp _thmc_preRiverComp
    _thmc_preTurnComp _thmc_rcpp_hello_world
我认为我在写Roxygen注释方面做得很好，所以我一定在使用它们的地方使用了错误的函数。明确地说，我可以library(thmc)并且不会引发任何错误，但是不会导出任何函数。我可以看到这是因为当我键入search()时，它会产生

 [1] ".GlobalEnv"        "package:thmc"      "devtools_shims"    "tools:rstudio"     "package:stats"    
 [6] "package:graphics"  "package:grDevices" "package:utils"     "package:datasets"  "package:methods"  
[11] "Autoloads"         "org:r-lib"         "package:base" 
这是我的src/do_comps.cpp文件：

#include <Rcpp.h>
#include "easy_header.h"

using namespace Rcpp;


//' Calculate pre-flop probability estimates
//' 
//' @param your_cards your cards as a length-4 character vector.
//' @param num_sims number of simulations.
//' @param num_folders number of folders.
//' @param num_oppo number of opponents.
//' @export
// [[Rcpp::export]]
CharacterVector preFlopComp(CharacterVector your_cards, IntegerVector num_sims, IntegerVector num_folders,
                            IntegerVector num_oppo) {

  unsigned int _num_folders = num_folders[0];
  unsigned int _num_sims = num_sims[0];
  unsigned int _num_oppo = num_oppo[0];
  std::string val1 = Rcpp::as<std::string>(your_cards[0]);
  std::string suit1 = Rcpp::as<std::string>(your_cards[1]);
  std::string val2 = Rcpp::as<std::string>(your_cards[2]);
  std::string suit2 = Rcpp::as<std::string>(your_cards[3]);

  double percWon, percTie;

  // construct simulator object and add folders  
  Simulator s(_num_sims, _num_oppo); 
  for(size_t i = 0; i < _num_folders; ++i)
    s.addFolder();

  // add your cards
  s.addYouCard(Card::fromString(val1, suit1));
  s.addYouCard(Card::fromString(val2, suit2));

  // get final numbers
  s.doSim(percWon, percTie);

  return CharacterVector::create(s.prettyResults());
}
[请注意，在文档文件中有两行带有单词“ export”。在R/RcppExports.R中，我有

# Generated by using Rcpp::compileAttributes() -> do not edit by hand
# Generator token: 10BE3573-1514-4C36-9D1C-5A225CD40393

#' Calculate pre-flop probability estimates
#' 
#' @param your_cards your cards as a length-4 character vector.
#' @param num_sims number of simulations.
#' @param num_folders number of folders.
#' @param num_oppo number of opponents.
#' @export
preFlopComp <- function(your_cards, num_sims, num_folders, num_oppo) {
    .Call(`_thmc_preFlopComp`, your_cards, num_sims, num_folders, num_oppo)
}
也许是我的NAMESPACE文件。我已经尝试了一些方法。最近的尝试是使用我发现的建议here和here：

# Generated by roxygen2: do not edit by hand

importFrom(Rcpp, sourceCpp)
useDynLib(thmc, .registration=TRUE)
export(postRiverComp)
export(preFlopComp)
export(preRiverComp)
export(preTurnComp)
运行devtools::check()确实会通过删除importFrom和useDynLib调用来更改此文件。根据exportPattern("^[[:alpha:]]+")中的建议，我也尝试添加行official vignette，但这没有用。 

[另外，我想我已经检查了这些答案here给出的所有框，但仍然无济于事。

当我尝试从R包中加载某些c ++函数时，会遇到一些麻烦。运行devtools :: check（）会产生>检查R代码中是否可能存在问题... ...

Answer 1

importFrom中的useDynLib和NAMESPACE调用很重要。切换到手动创建的NAMESPACE文件或添加