使用内联 Rcpp 从全局环境中读取变量? [英] Read variables from global environment with inline Rcpp?
问题描述
我正在遵循 Rcpp 介绍 Vignette 中的示例,尝试使用内联.
I'm following the example from the Rcpp intro Vignette, trying it with inline.
f<-cxxfunction(signature(), plugin="Rcpp", body="
Environment global = Environment::global_env();
std::vector<double> vx = global['x'];
")
但是我得到一个编译错误.
but I get a compile error.
file12384509.cpp: In function 'SEXPREC* file12384509()':
file12384509.cpp:31: error: invalid use of incomplete type 'struct SEXPREC'
C:/PROGRA~1/R/R-211~1.1/include/Rinternals.h:333: error: forward declaration of 'struct SEXPREC'
file12384509.cpp:31: error: conversion from 'SEXPREC' to non-scalar type 'std::vector<double, std::allocator<double> >' requested
make: *** [file12384509.o] Error 1
ERROR(s) during compilation: source code errors or compiler configuration errors!
Program source:
1: // includes from the plugin
2:
3: #include <Rcpp.h>
4:
5:
6: #ifndef BEGIN_RCPP
7: #define BEGIN_RCPP
8: #endif
9:
10: #ifndef END_RCPP
11: #define END_RCPP
12: #endif
13:
14: using namespace Rcpp;
15:
16:
17: // user includes
18:
19:
20: // declaration
21: extern "C" {
22: SEXP file12384509( ) ;
23: }
24:
25: // definition
26:
27: SEXP file12384509( ){
28: BEGIN_RCPP
29:
30: Environment global = Environment::global_env();
31: std::vector<double> vx = global['x'];
32:
33: END_RCPP
34: }
35:
36:
Error in compileCode(f, code, language = language, verbose = verbose) :
Compilation ERROR, function(s)/method(s) not created! file12384509.cpp: In function 'SEXPREC* file12384509()':
file12384509.cpp:31: error: invalid use of incomplete type 'struct SEXPREC'
C:/PROGRA~1/R/R-211~1.1/include/Rinternals.h:333: error: forward declaration of 'struct SEXPREC'
file12384509.cpp:31: error: conversion from 'SEXPREC' to non-scalar type 'std::vector<double, std::allocator<double> >' requested
make: *** [file12384509.o] Error 1
出了什么问题,有没有办法解决这个问题?这只是玩具示例,我有一个更重要的复杂问题,取决于对此的答案.
What is wrong and is there a way to fix this? This is just the toy example, I have a more important complicated problem depending on the answer to this.
推荐答案
感谢您对 的关注Rcpp!Romain 和我通常建议在 rcpp-devel 列表中提出问题;你可能会在那里得到一些更合适的眼球.
Thanks for your interest in Rcpp! Romain and I usually suggest that questions be posed on the rcpp-devel list; you are probably getting a few more appropriate eyeballs there.
在这里,您陷入了单引号和双引号的陷阱.切换这些使一切正常.我还在玩的时候对代码重新排序/重新排列/重新标记:
Here, you fell into a trap of single versus double quotes. Switching these around make it all work. I also reordered / rearranged / relabeled the code a little while I was playing with it:
> f <- cxxfunction(signature(),
+ body=' Environment e = Environment::global_env();
+ std::vector<double> vx = e["x"];
+ return wrap(vx); ',
+ plugin="Rcpp")
> x <- 3:6
> f()
[1] 3 4 5 6
>
就其价值而言,这里是相同的,但传递了一个环境.这就是我首先玩的,而且我更喜欢它
For what it's worth, here is the same but passing an environment down. That's what I played with first and which I somehow like better
f <- cxxfunction(signature(env="environment"),
body=' Environment e(env);
std::vector<double> vx = e["x"];
return wrap(vx); ',
plugin="Rcpp")
env <- new.env()
env[["x"]] <- 1:4
f(env)
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