Rcpp编译器用返回值标记错误-无提示

Question

我正在尝试使用Rcpp函数来加速某些R代码。一个功能是让我可以编译，而我不知道为什么编译器会抱怨return参数。我声明了要返回NumericVector的函数，结果是NumericVector，但是编译器抱怨return参数无效。

Rcpp是版本0.12.18，R是Microsoft Open R 3.5.3]

cppFunction('NumericVector NNE(IntegerVector X, IntegerVector Y, IntegerVector XY, IntegerVector xy, NumericVector P, int radius ) {

  int n = X.size();
  NumericVector vN[n];
  NumericVector vSum[n];
  NumericVector vAvg[n];


  // for each xy determine neighborhood Sum and count (N)
  for(int i=0; i<n; i++) {
    vN[i] = 0.0;
    vSum[i] = 0.0;

    // traverse neighborhood, if the xy exists in the input
    // vector then accumulate the values, otherwise ignore

    for(int dx=-1*radius; dx<=radius; dx++) {
      for(int dy=-1*radius; dy<=radius; dy++) {

        // construct an xy index for the neighborhood die
        xy[0] = ( (X[i]+dx) * 10000 ) + (Y[i]+dy);

        // check to see if index above exists in input set
        IntegerVector m = Rcpp::match(xy, XY);

        // if valid then accumulate and count
        if(m[0] != NA_INTEGER) {
          vN[i] = vN[i] + 1.0;
          vSum[i] = vSum[i] + P[ m[0] ];
        }
      }
    }

    vAvg[i] = vSum[i] / vN[i];
  }

  return vAvg;
}')

令人困惑的编译器消息如下：

C:/RBuildTools/3.5/mingw_64/bin/g++ -m64 -I"C:/PROGRA~1/MICROS~3/ROPEN~1/R-35~1.3/include" -DNDEBUG   -I"D:/Users/ka/Documents/R/win-library/3.5/Rcpp/include" -I"D:/Users/ka/AppData/Local/Temp/4/RtmpeGKfUg/sourceCpp-x86_64-w64-mingw32-0.12.18"   -I"C:/a/w/1/s/vendor/extsoft/include"     -O2 -Wall  -mtune=core2 -c filefcc651c7fa9.cpp -o filefcc651c7fa9.o
filefcc651c7fa9.cpp: In function 'Rcpp::NumericVector NNE(Rcpp::IntegerVector, Rcpp::IntegerVector, Rcpp::IntegerVector, Rcpp::IntegerVector, Rcpp::NumericVector, int)':
filefcc651c7fa9.cpp:42:10: error: invalid conversion from 'Rcpp::NumericVector* {aka Rcpp::Vector<14, Rcpp::PreserveStorage>*}' to 'const int&' [-fpermissive]
   return vAvg;
          ^
In file included from D:/Users/ka/Documents/R/win-library/3.5/Rcpp/include/Rcpp/Vector.h:52:0,
                 from D:/Users/ka/Documents/R/win-library/3.5/Rcpp/include/Rcpp.h:40,
                 from filefcc651c7fa9.cpp:1:
D:/Users/ka/Documents/R/win-library/3.5/Rcpp/include/Rcpp/vector/Vector.h:128:5: note: initializing argument 1 of 'Rcpp::Vector<RTYPE, StoragePolicy>::Vector(const int&) [with int RTYPE = 14; StoragePolicy = Rcpp::PreserveStorage]'
     Vector( const int& size ) {
     ^
make: *** [C:/PROGRA~1/MICROS~3/ROPEN~1/R-35~1.3/etc/x64/Makeconf:215: filefcc651c7fa9.o] Error 1
Error in sourceCpp(code = code, env = env, rebuild = rebuild, cacheDir = cacheDir,  : 
  Error 1 occurred building shared library.

Answer 1

就编译器而言，

您有一个miniscule错误呈现变量“坏”，然后您误解了“坏”变量的拒绝返回是另一个问题。

发生。我们都去过那里。

这里是已修复的代码。简而言之，您需要使用NumeriVector x(n);和round而不是平方括号（因为后者表示先后用C和C ++表示的数组）。

代码

我也将其转换为sourceCpp()的输入，鉴于功能的长度，此输入会更容易。

#include <Rcpp.h>

using namespace Rcpp;

// [[Rcpp::export]]
NumericVector NNE(IntegerVector X, IntegerVector Y, IntegerVector XY,
                  IntegerVector xy, NumericVector P, int radius ) {

  int n = X.size();
  NumericVector vN(n);
  NumericVector vSum(n);
  NumericVector vAvg(n);

  // for each xy determine neighborhood Sum and count (N)
  for(int i=0; i<n; i++) {
    vN[i] = 0.0;
    vSum[i] = 0.0;

    // traverse neighborhood, if the xy exists in the input
    // vector then accumulate the values, otherwise ignore

    for(int dx=-1*radius; dx<=radius; dx++) {
      for(int dy=-1*radius; dy<=radius; dy++) {

        // construct an xy index for the neighborhood die
        xy[0] = ( (X[i]+dx) * 10000 ) + (Y[i]+dy);

        // check to see if index above exists in input set
        IntegerVector m = Rcpp::match(xy, XY);

        // if valid then accumulate and count
        if(m[0] != NA_INTEGER) {
          vN[i] = vN[i] + 1.0;
          vSum[i] = vSum[i] + P[ m[0] ];
        }
      }
    }

    vAvg[i] = vSum[i] / vN[i];
  }

  return vAvg;
}

/*** R
cat("Built\n")
*/

输出

由于我们没有参考数据，所以我只能证明它是内置的：

R> sourceCpp("~/git/stackoverflow/61377960/answer.cpp")

R> cat("Built\n")
Built
R>