Rcpp - 在 sourceCpp 引用的文件中使用多个 C++ 函数? [英] Rcpp - Use multiple C++ functions in file referenced by sourceCpp?

问题描述

我希望这不是太明显，因为我已经搜索了一整天，但找不到答案.

I hope this isn't too obvious, as I've searched all day and can't find the answer.

假设我有以下 R 文件:

Say I have the following R file:

library(Rcpp)
sourceCpp("cfile.cpp")

giveOutput(c(1,2,3))

它编译以下 C++ 文件:

And it compiles the following C++ file:

#include <Rcpp>
using namespace Rcpp;
// [[Rcpp::export]]

NumericVector plusTwo(NumericVector x){
  NumericVector out = x + 2.0;

  return out;
}

NumericVector giveOutput(NumericVector a){

NumericVector b = plusTwo(a);
return b;
}

无论我尝试什么，Rcpp 预处理器都会使 plusTwo() 可用，而 giveOutput() 根本不可用.我能找到的文档说这是应该创建一个包的点，但在阅读包小插图后，它似乎比我需要的要复杂一个数量级.

No matter what I try, the Rcpp preprocessor makes plusTwo() available, and giveOutput() not at all. The documentation I've been able to find says that this is the point at which one should create a package, but after reading the package vignette it seems an order of magnitude more complicated than what I need.

在 giveOutput() 中没有明确定义 plusTwo()，我该怎么办?

Short of explicitly defining plusTwo() inside giveOutput(), what can I do?

推荐答案

您应该在要导出的每个函数前使用 export 属性.因此，通过将您的文件更正为

You are expected to use the export attribute in front of every function you wanted exported. So by correcting your file to

#include <Rcpp.h>

using namespace Rcpp;

// [[Rcpp::export]]
NumericVector plusTwo(NumericVector x){
  NumericVector out = x + 2.0;
  return out;
}

// [[Rcpp::export]]
NumericVector giveOutput(NumericVector a){
  NumericVector b = plusTwo(a);
  return b;
}

我得到了想要的行为:

R> sourceCpp("/tmp/patrick.cpp")
R> giveOutput(1:3)
[1] 3 4 5
R> plusTwo(1:3)
[1] 3 4 5
R> 

哦，创建一个包就像调用 Rcpp.package.skeleton() 一样简单(但请阅读它的帮助页面，特别是 attributes 参数).我知道至少有一个 CRAN 包开始了你从这里开始的方式，很明显通过 Rcpp.package.skeleton()...

Oh, and creating a package is as easy as calling Rcpp.package.skeleton() (but read its help page, particularly for the attributes argument). I know of at least one CRAN package that started how you started here and clearly went via Rcpp.package.skeleton()...

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