使用Rcpp从C ++调用用户定义的R函数

I have an R code with a bunch of user-defined R functions. I'm trying to make the code run faster and of course the best option is to use Rcpp. My code involves functions that call each other. Therefore, If I write some functions in C++, I should be able to call and to run some of my R functions in my c++ code. In a simple example consider the code below in R:

我有一个带有一堆用户定义的R函数的R代码。我正在努力使代码运行得更快,当然最好的选择是使用Rcpp。我的代码涉及相互调用的函数。因此,如果我用C ++编写一些函数,我应该能够在我的c ++代码中调用并运行一些R函数。在一个简单的例子中,考虑R中的以下代码:

mySum <- function(x, y){
 return(2*x + 3*y)
}
x <<- 1
y <<- 1

Now consider the C++ code in which I'm trying to access the function above:

现在考虑我正在尝试访问上述函数的C ++代码:

#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
int mySuminC(){
 Environment myEnv = Environment::global_env();
 Function mySum = myEnv["mySum"];
 int x = myEnv["x"];
 int y = myEnv["y"];
 return wrap(mySum(Rcpp::Named("x", x), Rcpp::Named("y", y)));
 }

When I source the file in R with the inline function sourceCpp(), I get the error:

当我使用内联函数sourceCpp()在R中获取文件时,我收到错误:

 "invalid conversion from 'SEXPREC*' to int

Could anyone help me on debugging the code? Is my code efficient? Can it be summarized? Is there any better idea to use mySum function than what I did in my code?

有人可以帮我调试代码吗?我的代码有效吗?可以归纳一下吗?使用mySum函数比我在代码中做的更好吗?

Thanks very much for your help.

非常感谢您的帮助。

1 个解决方案

#1

You declare that the function should return an int, but use wrap which indicates the object returned should be a SEXP. Moreover, calling an R function from Rcpp (through Function) also returns a SEXP.

您声明该函数应该返回一个int,但是使用wrap表示返回的对象应该是SEXP。此外,从Rcpp(通过Function)调用R函数也会返回SEXP。

You want something like:

你想要的东西:

#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
SEXP mySuminC(){
  Environment myEnv = Environment::global_env();
  Function mySum = myEnv["mySum"];
  int x = myEnv["x"];
  int y = myEnv["y"];
  return mySum(Rcpp::Named("x", x), Rcpp::Named("y", y));
}

(or, leave function return as int and use as<int> in place of wrap).

(或者,将函数返回为int并使用代替换行)。

That said, this is kind of non-idiomatic Rcpp code. Remember that calling R functions from C++ is still going to be slow.

也就是说,这是一种非惯用的Rcpp代码。请记住,从C ++调用R函数仍然会很慢。

#1