C++ 在Rcpp中检测和省略std向量中的na值
我有一个std::向量;在检查其中是否存在Na值(如果存在Na值,则明显移除Na值)之后,需要对其元素进行求和。我必须在Rcpp里做。现在,对于Rcpp中的数值向量(NumericVector);这非常简单,代码如下所示:C++ 在Rcpp中检测和省略std向量中的na值,c++,r,rcpp,C++,R,Rcpp,我有一个std::向量;在检查其中是否存在Na值(如果存在Na值,则明显移除Na值)之后,需要对其元素进行求和。我必须在Rcpp里做。现在,对于Rcpp中的数值向量(NumericVector);这非常简单,代码如下所示: cppFunction(" double res ( NumericVector x){ NumericVector v = x[! is_na(x)]; return sum(v); }
cppFunction("
double res ( NumericVector x){
NumericVector v = x[! is_na(x)];
return sum(v);
}
")
。所以对于向量“x”,它很容易得出如下的和:
x<- c(NaN,1,2)
res(x)
[1] 3
x您应该能够使用(也可以打开)将Rcpp Sugar的向量化习惯用法(它与R一样对NA测试进行了向量化)带到任何iterable容器中,因此也可以使用STL容器
有关将不同向量类型和类组合成单个标量表达式的示例,请参见示例:
// [[Rcpp::export]]
Rcpp::NumericVector example_manually_hooked() {
// We manually hooked std::list in to RcppHoney so we'll create one
std::list< int > l;
l.push_back(1); l.push_back(2); l.push_back(3); l.push_back(4); l.push_back(5);
// std::vector is already hooked in to RcppHoney in default_hooks.hpp so
// we'll create one of those too
std::vector< int > v(l.begin(), l.end());
// And for good measure, let's create an Rcpp::NumericVector which is
// also hooked by default
Rcpp::NumericVector v2(v.begin(), v.end());
// Now do some weird operations incorporating std::vector, std::list,
// Rcpp::NumericVector and some RcppHoney functions and return it. The
// return value will be equal to the following R snippet:
// v <- 1:5
// result <- 42 + v + v + log(v) - v - v + sqrt(v) + -v + 42
// We can store our result in any of RcppHoney::LogicalVector,
// RcppHoney::IntegerVector, or RcppHoney::NumericVector and simply return
// it to R. These classes inherit from their Rcpp counterparts and add a
// new constructor. The only copy of the data, in this case, is when we
// assign our expression to retval. Since it is then a "native" R type,
// returning it is a shallow copy. Alternatively we could write this as:
// return Rcpp::wrap(1 + v + RcppHoney::log(v) - v - 1
// + RcppHoney::sqrt(v) + -v2);
RcppHoney::NumericVector retval
= 42 + l + v + RcppHoney::log(v) - v - l + RcppHoney::sqrt(v) + -v2
+ 42;
return retval;
}
/[[Rcpp::export]]
Rcpp::NumericVector示例\u手动\u钩住(){
//我们手动将std::list连接到RcppHoney,因此我们将创建一个
标准::列表l;
l、 推回(1);l.推回(2);l.推回(3);l.推回(4);l.推回(5);
//std::vector已经挂接到默认的\u hooks.hpp中的RcppHoney,所以
//我们也将创建其中一个
向量v(l.begin(),l.end());
//为了更好地衡量,让我们创建一个Rcpp::NumericVector,它是
//默认情况下也挂接
Rcpp::NumericVector v2(v.begin(),v.end());
//现在结合std::vector、std::list做一些奇怪的操作,
//Rcpp::NumericVector和一些RcppHoney函数并返回它
//返回值将等于以下R代码段:
//v您应该能够使用(也启用)将Rcpp Sugar的向量化习惯用法(与R一样,它将NA测试向量化)带到任何可移植容器中,因此也可以使用STL容器
有关将不同向量类型和类组合成单个标量表达式的示例,请参见示例:
// [[Rcpp::export]]
Rcpp::NumericVector example_manually_hooked() {
// We manually hooked std::list in to RcppHoney so we'll create one
std::list< int > l;
l.push_back(1); l.push_back(2); l.push_back(3); l.push_back(4); l.push_back(5);
// std::vector is already hooked in to RcppHoney in default_hooks.hpp so
// we'll create one of those too
std::vector< int > v(l.begin(), l.end());
// And for good measure, let's create an Rcpp::NumericVector which is
// also hooked by default
Rcpp::NumericVector v2(v.begin(), v.end());
// Now do some weird operations incorporating std::vector, std::list,
// Rcpp::NumericVector and some RcppHoney functions and return it. The
// return value will be equal to the following R snippet:
// v <- 1:5
// result <- 42 + v + v + log(v) - v - v + sqrt(v) + -v + 42
// We can store our result in any of RcppHoney::LogicalVector,
// RcppHoney::IntegerVector, or RcppHoney::NumericVector and simply return
// it to R. These classes inherit from their Rcpp counterparts and add a
// new constructor. The only copy of the data, in this case, is when we
// assign our expression to retval. Since it is then a "native" R type,
// returning it is a shallow copy. Alternatively we could write this as:
// return Rcpp::wrap(1 + v + RcppHoney::log(v) - v - 1
// + RcppHoney::sqrt(v) + -v2);
RcppHoney::NumericVector retval
= 42 + l + v + RcppHoney::log(v) - v - l + RcppHoney::sqrt(v) + -v2
+ 42;
return retval;
}
/[[Rcpp::export]]
Rcpp::NumericVector示例\u手动\u钩住(){
//我们手动将std::list连接到RcppHoney,因此我们将创建一个
标准::列表l;
l、 推回(1);l.推回(2);l.推回(3);l.推回(4);l.推回(5);
//std::vector已经挂接到默认的\u hooks.hpp中的RcppHoney,所以
//我们也将创建其中一个
向量v(l.begin(),l.end());
//为了更好地衡量,让我们创建一个Rcpp::NumericVector,它是
//默认情况下也挂接
Rcpp::NumericVector v2(v.begin(),v.end());
//现在结合std::vector、std::list做一些奇怪的操作,
//Rcpp::NumericVector和一些RcppHoney函数并返回它
//返回值将等于以下R代码段:
//v分配一些中间向量很容易,但效率不高。最好使用循环,它也适用于std::vector。这里有一些替代想法:分配一些中间向量很容易,但效率不高。最好使用循环,它也适用于std::vector。一些替代方案这里有一些积极的想法: