Rcpp基础整理 R语言学习Rcpp基础知识全面整理

library(Rcpp)
Sys.setenv("PKG_CXXFLAGS"="-std=c++11")
sourceCpp("test.cpp")

#include <Rcpp.h>
using namespace Rcpp;
//[[Rcpp::export]]

// [[Rcpp::depends(RcppArmadillo)]]
#include <RcppArmadillo.h>
#include <Rcpp.h>
using namespace Rcpp;
using namespace arma;
// [[Rcpp::export]]

>mod=lm(Y~X);

NumericVector resid = as<NumericVector>(mod["residuals"]);
NumericVector fitted = as<NumericVector>(mod["fitted.values"]);

std::vector<double> vec;
vec = as<std::vector<double>>(x);

arma::vec long_vec(16,arma::fill::randn);
vector<double> long_vec2 = conv_to<vector<double>>::from(long_vec);
NumericVector output = wrap(long_vec2);

//1. Vector
NumericVector V1(n);//创立了一个长度为n的默认初始化的数值型向量V1。
NumericVector V2=NumericVector::create(1, 2, 3); //创立了一个数值型向量V2，并初始化使其含有三个数1，2，3。
LogicalVector V3=LogicalVector::create(true,false,R_NaN);//创立了一个逻辑型变量V3。如果将其转化为R Object，则其含有三个值TRUE, FALSE, NA。
//2. Matrix
NumericMatrix M1(nrow,ncol);//创立了一个nrow*ncol的默认初始化的数值型矩阵。
//3. Multidimensional Array
NumericVector out=NumericVector(Dimension(2,2,3));//创立了一个多维数组。然而我不知道有什么卵用。。
//4. List
NumericMatrix y1(2,2);
NumericVector y2(5);
List L=List::create(Named("y1")=y1,
                    Named("y2")=y2);

//5. DataFrame
NumericVector a=NumericVector::create(1,2,3);
CharacterVector b=CharacterVector::create("a","b","c");
std::vector<std::string> c(3);
c[0]="A";c[1]="B";c[2]="C";
DataFrame DF=DataFrame::create(Named("col1")=a,
                               Named("col2")=b,
                               Named("col3")=c);

template <typename T>
T square( const T& x){
    return x * x ;
}
sapply( seq_len(10), square<int> ) ;

template <typename T>
struct square : std::unary_function<T,T> {
    T operator()(const T& x){
    return x * x ;
    }
}
sapply( seq_len(10), square<int>() ) ;

#include <Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export]]
double sum3(NumericVector x) {
  double total = 0;
  NumericVector::iterator it;
  for(it = x.begin(); it != x.end(); ++it) {
    total += *it;
  }
  return total;
}

#include <algorithm>
#include <Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export]]
IntegerVector findInterval2(NumericVector x, NumericVector breaks) {
  IntegerVector out(x.size());
  NumericVector::iterator it, pos;
  IntegerVector::iterator out_it;
  for(it = x.begin(), out_it = out.begin(); it != x.end(); 
      ++it, ++out_it) {
    pos = std::upper_bound(breaks.begin(), breaks.end(), *it);
    *out_it = std::distance(breaks.begin(), pos);
  }
  return out;
}

#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
List rleC(NumericVector x) {
  std::vector<int> lengths;
  std::vector<double> values;

  // Initialise first value
  int i = 0;
  double prev = x[0];
  values.push_back(prev);
  lengths.push_back(1);

  NumericVector::iterator it;
  for(it = x.begin() + 1; it != x.end(); ++it) {
    if (prev == *it) {
      lengths[i]++;
    } else {
      values.push_back(*it);
      lengths.push_back(1);

      i++;
      prev = *it;
    }
  }
  return List::create(
    _["lengths"] = lengths, 
    _["values"] = values
  );
}

Rcpp::Environment stats("package:stats");
Rcpp::Function rnorm = stats["rnorm"];
return rnorm(10, Rcpp::Named("sd", 100.0));

Rcpp::Environment global = Rcpp::Environment::global_env();//获取全局环境并赋值给Environment型变量global
Rcpp::NumericVector tmp = global["x"];//获取x
tmp=pow(tmp,2);//平方
global["x"]=tmp;//将新的值赋予到全局环境中的x

x=c(1,2,3);
funR<-function(x){
  return (-x);
}

#include <Rcpp.h>
using namespace Rcpp;
// [[Rcpp::export]]
NumericVector funC() {
  Rcpp::Environment global =
    Rcpp::Environment::global_env();
  Rcpp::Function funRinC = global["funR"];
  Rcpp::NumericVector tmp = global["x"];
  return funRinC(tmp);
}

// Dimension最多设置三个维数
output.attr("dim") = Dimension(3,4,2);
// 可以给.attr(“dim”)赋予一个向量，则可以设置超过三个维数
NumericVector dim = NumericVector::create(2,2,2,2);
output.attr("dim") = dim;

// 返回一个3*3*2数组
RObject func(){
  arma::vec long_vec(18,arma::fill::randn);
  vector<double> long_vec2 = conv_to<vector<double>>::from(long_vec);
  NumericVector output = wrap(long_vec2);
  output.attr("dim")=Dimension(3,3,2);
  return wrap(output);
}

// 返回一个2*2*2*2数组 
// 注意con_to<>::from()
RObject func(){
  arma::vec long_vec(16,arma::fill::randn);
  vector<double> long_vec2 = conv_to<vector<double>>::from(long_vec);
  NumericVector output = wrap(long_vec2);
  NumericVector dim = NumericVector::create(2,2,2,2);
  output.attr("dim")=dim;
  return wrap(output);
}

vector<double> func(NumericVector x){
  vector<double> vec;
  vec = as<vector<double>>(x);
  return vec;
}
NumericVector func(NumericVector x){
  vector<double> vec;
  vec = as<vector<double>>(x);
  return wrap(vec);
}
RObject func(NumericVector x){
  vector<double> vec;
  vec = as<vector<double>>(x);
  return wrap(vec);
}

vector<vector<double>> func(NumericVector x) {
  vector<vector<double>> mat;
  for (int i=0;i!=3;++i){
    mat.push_back(as<vector<double>>(x));
  }
  return mat;
}
RObject func(NumericVector x) {
  vector<vector<double>> mat;
  for (int i=0;i!=3;++i){
    mat.push_back(as<vector<double> >(x));
  }
  return wrap(mat);
}

NumericMatrix func(){
  arma::mat A(3,4,arma::fill::randu);
  return wrap(A);
}
arma::mat func(){
  arma::mat A(3,4,arma::fill::randu);
  return A;
}

arma::cube func(){
  arma::cube A(3,4,5,arma::fill::randu);
  return A;
}
RObject func(){
  arma::cube A(3,4,5,arma::fill::randu);
  return wrap(A);
}

RObject func() {
  arma::cube A(3,4,2,arma::fill::randu);
  arma::cube B(3,4,2,arma::fill::randu);
  arma::field <arma::cube> F(2,1);
  F(0)=A;
  F(1)=B;
  return wrap(F);
}