Question

解决这两个职位的问题 1. Convert char to int in C and C++
2. http://lists.r-forge.r-project.org/pipermail/rcpp-devel/2010-July/000932.html

我试图将Rcpp矩阵（NumericMatrix等）中的rownames作为IntegerVector。

在R中，这将是：

as.integer(rownames(x)) # where x is a matrix

我尝试过以两种不同的方式进行投射，并且遇到了不同的编译错误：

尝试1

cppFunction('IntegerVector rownames1(NumericMatrix x) {
            List dimnames = x.attr("dimnames");
            CharacterVector rownames = dimnames[0];
            IntegerVector out(dimnames.size());
            for (int i= 0; i < out.size(); i++) {
              out[i] = (int) rownames[i]; // cast via (int)
            }

            return (IntegerVector) dimnames[0];}')

file1b9c6dec3c12.cpp：在函数＆＃39; Rcpp :: IntegerVector rownames1（Rcpp :: NumericMatrix）＆＃39;： file1b9c6dec3c12.cpp：11：40：错误：从类型＆＃39; Rcpp :: Vector＆lt; 16＆gt; :: Proxy {aka Rcpp :: internal :: string_proxy＆lt; 16＆gt;}＆＃39;输入＆＃39; int＆＃39; make：*** [file1b9c6dec3c12.o]错误1 警告信息： run command＆＃39; make -f＆＃34; C：/PROGRA~1/R/R-32~1.2/etc/x64/Makeconf" -f＆＃34; C：/PROGRA~1/R/R-32~1.2/share/make/winshlib.mk" SHLIB_LDFLAGS =＆＃39; $（SHLIB_CXXLDFLAGS）＆＃39; SHLIB_LD =＆＃39; $（SHLIB_CXXLD）＆＃39; SHLIB =＆＃34; sourceCpp_23.dll＆＃34; WIN = 64 TCLBIN = 64 OBJECTS =＆＃34; file1b9c6dec3c12.o＆＃34;＆＃39;有状态2

尝试2

cppFunction('IntegerVector rownames1(NumericMatrix x) {
            List dimnames = x.attr("dimnames");
            CharacterVector rownames = dimnames[0];
            IntegerVector out(dimnames.size());
            for (int i= 0; i < out.size(); i++) {
              out[i] = rownames[i] + "0"; // cast as suggested in SO post linked above
            }

            return (IntegerVector) dimnames[0];}')

file1b9c71d25b92.cpp：在函数＆＃39; Rcpp :: IntegerVector rownames1（Rcpp :: NumericMatrix）＆＃39;： file1b9c71d25b92.cpp：11：38：错误：＆＃39;运算符的模糊重载 - ＆＃39; in＆＃39; Rcpp :: Vector :: operator [with int RTYPE = 16，StoragePolicy = Rcpp :: PreserveStorage，Rcpp :: Vector :: Proxy = Rcpp :: internal :: string_proxy＆lt; 16＆gt ;, R_xlen_t = long long int ]（（（long long int）i）） - ＆＃34; 0＆＃34;＆＃39; file1b9c71d25b92.cpp:11:38：注意：候选人是： file1b9c71d25b92.cpp:11:38：注意：operator-（const char *，const char *） file1b9c71d25b92.cpp:11:38：注意：operator-（const char *，const char *） file1b9c71d25b92.cpp:11:38：注意：operator-（char *，char *） make：*** [file1b9c71d25b92.o]错误1 警告信息： run command＆＃39; make -f＆＃34; C：/PROGRA~1/R/R-32~1.2/etc/x64/Makeconf" -f＆＃34; C：/PROGRA~1/R/R-32~1.2/share/make/winshlib.mk" SHLIB_LDFLAGS =＆＃39; $（SHLIB_CXXLDFLAGS）＆＃39; SHLIB_LD =＆＃39; $（SHLIB_CXXLD）＆＃39; SHLIB =＆＃34; sourceCpp_21.dll＆＃34; WIN = 64 TCLBIN = 64 OBJECTS =＆＃34; file1b9c71d25b92.o＆＃34;＆＃39;有状态2

任何帮助表示赞赏！

Answer 1

您可以使用cstdlib函数atoi将const char*转换为int。例如，

#include <Rcpp.h>

// [[Rcpp::export]]
Rcpp::IntegerVector rownames1(Rcpp::NumericMatrix x) {
    Rcpp::List dimnames = x.attr("dimnames");
    Rcpp::CharacterVector rownames = dimnames[0];
    Rcpp::IntegerVector out(rownames.size());

    std::transform(rownames.begin(), rownames.end(), out.begin(), std::atoi);

    return out;
}


/*** R

M <- matrix(
    1.5:16.5, nrow = 4, 
    dimnames = list(1:4, 1:4))
##
R> all.equal(rownames1(M), as.integer(row.names(M)))
#[1] TRUE

*/

如何在Rcpp中获取整数rownames？

尝试1

尝试2

1 个答案: