[Rcpp-devel] inconsistent is_na() vs. is.na()

[Romain Francois]

Hi,

The question is that do we want to be consistent with R or do we want 
something that makes sense.

I believe that is_na should test if its argument is NA, and is_nan 
should check if is NaN

Romain

Le 02/10/13 13:31, Thomas Tse a écrit :
> Hi,
>
> is_na() does not handles R's NaN correctly, for the below test.cpp:
>
> #include <Rcpp.h>
> using namespace Rcpp;
> using namespace std;
>
> // [[Rcpp::export]]
> void test (NumericVector x)
> {
>    LogicalVector y1 = is_na(x);
>    LogicalVector y2 = is_finite(x);
>    LogicalVector y3 = is_infinite(x);
>    LogicalVector y4 = is_nan(x);
>
>    Rcpp::Rcout << "x= ";
>    for(int i = 0; i < x.size(); i++) Rcpp::Rcout << x[i] << " ";
>    Rcpp::Rcout << std::endl;
>
>    Rcpp::Rcout << "is_na(x)= ";
>    for(int i = 0; i < y1.size(); i++) Rcpp::Rcout << y1[i] << " ";
>    Rcpp::Rcout << std::endl;
>
>    Rcpp::Rcout << "is_finite(x)= ";
>    for(int i = 0; i < y2.size(); i++) Rcpp::Rcout << y2[i] << " ";
>    Rcpp::Rcout << std::endl;
>
>    Rcpp::Rcout << "is_infinite(x)= ";
>    for(int i = 0; i < y3.size(); i++) Rcpp::Rcout << y3[i] << " ";
>    Rcpp::Rcout << std::endl;
>
>    Rcpp::Rcout << "is_nan(x)= ";
>    for(int i = 0; i < y4.size(); i++) Rcpp::Rcout << y4[i] << " ";
>    Rcpp::Rcout << std::endl;
> }
>
>
>
> and the below codes in R, we see that is_na() in C++ does NOT match is.na() in R (in NaN case):
>
>> sourceCpp('test.cpp');
>> x <- c(1:3, NA, 4, Inf, -Inf, NaN);
>
>> test(x);
> x= 1 2 3 1.#QNAN 4 1.#INF -1.#INF -1.#IND
> is_na(x)= 0 0 0 1 0 0 0 0
> is_finite(x)= 1 1 1 0 1 0 0 0
> is_infinite(x)= 0 0 0 0 0 1 1 0
> is_nan(x)= 0 0 0 0 0 0 0 1
>>   is.na(x);       # !!! DIFFERENT when dealing with NaN
> [1] FALSE FALSE FALSE  TRUE FALSE FALSE FALSE  TRUE
>> is.finite(x);   # same
> [1]  TRUE  TRUE  TRUE FALSE  TRUE FALSE FALSE FALSE
>> is.infinite(x); # same
> [1] FALSE FALSE FALSE FALSE FALSE  TRUE  TRUE FALSE
>> is.nan(x);      # same
> [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE  TRUE
>
>
> so, in .....\include\Rcpp\traits\is_na.h, we should modify like this:
> template <>
> inline bool is_na<REALSXP>( double x ){
> //return R_IsNA(x) ;
> return R_IsNA(x) || R_IsNaN(x);
> }
>
> template <>
> inline bool is_na<CPLXSXP>( Rcomplex x ){
> //return R_IsNA(x.r) || R_IsNA(x.i) ;
> return R_IsNA(x.r) || R_IsNA(x.i) || R_IsNaN(x.r) || R_IsNaN(x.i);
> }
>
>
>
> is it possible to apply this change in next release of Rcpp ?
>
> many thanks,
> Thomas


-- 
Romain Francois
Professional R Enthusiast
+33(0) 6 28 91 30 30