通过 RCpp 返回 NA [英] return NA via RCpp

问题描述

这里的新手 RCpp 问题:如何使 NumericVector 返回 NA 到 R?例如，假设我有一个 RCpp 代码，它将 NA 分配给向量的第一个元素.

Newbie RCpp question here: how can I make a NumericVector return NA to R? For example, suppose I have a RCpp code that assigns NA to the first element of a vector.

// [[RCpp::export]]
NumericVector myFunc(NumericVector x) {
   NumericVector y=clone(x);
   y[0]=NA; // <----- what's the right expression here?
   return y;
}

推荐答案

获得给定向量类型(NumericVector, IntegerVector, ...) 是使用静态的 get_na 方法.类似的东西:

The canonical way to get the correct NA for a given vector type (NumericVector, IntegerVector, ...) is to use the static get_na method. Something like:

y[0] = NumericVector::get_na() ;

FWIW，您的代码与 Rcpp11 一样工作，它知道如何从静态 Na_Proxy 实例 NA 转换为正确的缺失值对于目标类型.

FWIW, your code works as is with Rcpp11, which knows how to convert from the static Na_Proxy instance NA into the correct missing value for the target type.

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