[Rcpp-devel] type information about elements in Rcpp::List

[Romain François]

Le 9 juin 2014 à 21:40, Chaomei Lo <chaomeilo at gmail.com> a écrit :

>  
> I have a R list something like this -
>  
> op=list(a=200, b="test", c=4.5)
> when I pass it as an argument to Rcp Export function which the code looks like this in below.
>  
> ----------------------------------------
> int n = xlist.length();
> for (int I=0; I < n; I++) {
>   SEXP s = xlist[I];
>   if (Rf_isInteger(s)) {
>   //do something
>   }
>   else if (Rf_isNumerc(s)) {
>   //do other thing
>   }
>   else if (Rf_isString(s)) {
>   //do other thing
>   }
> }
>  
> However, both a and c go to the Rf_isNumeric if statement; but the first one is an integer,

no it’s not. 

> str( 200 )
 num 200
> str( 200L )
 int 200
> str( as.integer(200) )
 int 200

Suffix with « L » or use as.integer if you want an integer. 

Alternatively, Rcpp has is<>, so you can use 

if( is<int>(s) ) {
    ...
} 

Romain

> not sure why it did not go to into the Rf_isInteger if statement. 
>  
> Thanks.