以下Rcpp代码是生成相同编译错误的更大代码的最小可重现示例。似乎我无法将数字矩阵设置为列表,然后将列表再次设置为另一个矩阵。
#include <Rcpp.h>
using namespace Rcpp;
//[[Rcpp::export]]
List return_a(NumericMatrix a, NumericMatrix b){
//the function only returns the input matrix a
List result(1);
result(0) = a;
return(result);
}
//[[Rcpp::export]]
List wrapper_cpp(NumericMatrix a, NumericMatrix b){
//the function is a dummy wrapper for much more code
List Step1(1);
List results(1);
Step1 = return_a(a,b);
a = Step1(0);
results(0) = a;
return(results);
}
上面的代码给出了我缩短的以下编译错误:
error: ambiguous overload for 'operator=' (operand types are 'Rcpp::NumericMatrix {aka Rcpp::Matrix<14>}' and 'Rcpp::Vector<19>::Proxy ...
a = Step1(0);
我的真正功能要复杂得多。我需要在几个循环中操作矩阵,并且在每个步骤中,矩阵由列表中的每个函数返回。然后,我需要提取这些列表以进一步操作矩阵。如何才能做到这一点?
除了@Ralf已经提到的错误之外,你只是在尝试太多。有时我们需要一个中间步骤,因为模板魔术是......挑剔。以下作品。
#include <Rcpp.h>
using namespace Rcpp;
//[[Rcpp::export]]
List return_a(NumericMatrix a, NumericMatrix b){
//the function only returns the input matrix a
List result(1);
result(0) = a;
return(result);
}
//[[Rcpp::export]]
List wrapper_cpp(NumericMatrix a, NumericMatrix b){
//the function is a dummy wrapper for much more code
List results(1);
List Step1 = return_a(a,b);
NumericMatrix tmp = Step1(0);
results(0) = tmp;
return(results);
}
R> Rcpp::sourceCpp("~/git/stackoverflow/54771818/answer.cpp")
R> wrapper_cpp(matrix(1:4,2,2), matrix(4:1,2,2))
[[1]]
[,1] [,2]
[1,] 1 3
[2,] 2 4
R>