R help - Jan 2005 - type of list elements in .Call

Dear People,

Here is something I do not understand. Consider

*************************************************
foo.cc
*************************************************
#include <iostream>
#include <R.h>
#include <Rinternals.h>

using std::cout;
using std::endl;

extern "C"
{
   SEXP printlst(SEXP lst);
}

SEXP printlst(SEXP lst)
{
   for(int i=0; i<length(lst); i++)
     for(int j=0; j<length(VECTOR_ELT(lst, i)); j++)
       cout << INTEGER(VECTOR_ELT(lst, i))[j] << endl;
   return lst;
}
*************************************************
> dyn.load("foo.so")
> .Call("printlst", list(c(1,2),c(3,4)))
0
1072693248
0
1074266112
[[1]]
[1] 1 2

[[2]]
[1] 3 4

If I replace INTEGER by REAL I get
> dyn.load("foo.so")
> .Call("printlst", list(c(1,2),c(3,4)))
1
2
3
4
[[1]]
[1] 1 2

[[2]]
[1] 3 4

as I would expect. I thought that if the vectors in the list could be 
regarded as integer vectors, they would be, but apparently not. Is there 
any way I can tell R to regard them as integer vectors?

Thanks.                                                    Faheem.

On Mon, 31 Jan 2005, Faheem Mitha wrote:
> [SNIP]
> as I would expect. I thought that if the vectors in the list could be
> regarded as integer vectors, they would be, but apparently not. Is there
> any way I can tell R to regard them as integer vectors?
.Call("printlst", list(as.integer(c(1,2)),
                       as.integer(c(3,4)))

----------------------------------------------------------
SIGSIG -- signature too long (core dumped)

Please ask programming-related questions on the R-devel list -- see the 
advice in the posting guide.

On Mon, 31 Jan 2005, Faheem Mitha wrote:
>
> Dear People,
>
> Here is something I do not understand. Consider
>
> *************************************************
> foo.cc
> *************************************************
> #include <iostream>
> #include <R.h>
> #include <Rinternals.h>
>
> using std::cout;
> using std::endl;
>
> extern "C"
> {
>  SEXP printlst(SEXP lst);
> }
>
> SEXP printlst(SEXP lst)
> {
>  for(int i=0; i<length(lst); i++)
>    for(int j=0; j<length(VECTOR_ELT(lst, i)); j++)
>      cout << INTEGER(VECTOR_ELT(lst, i))[j] << endl;
>  return lst;
> }
> *************************************************
>
>> dyn.load("foo.so")
>> .Call("printlst", list(c(1,2),c(3,4)))
> 0
> 1072693248
> 0
> 1074266112
> [[1]]
> [1] 1 2
>
> [[2]]
> [1] 3 4
>
> If I replace INTEGER by REAL I get
>
>> dyn.load("foo.so")
>> .Call("printlst", list(c(1,2),c(3,4)))
> 1
> 2
> 3
> 4
> [[1]]
> [1] 1 2
>
> [[2]]
> [1] 3 4
>
> as I would expect. I thought that if the vectors in the list could be 
> regarded as integer vectors, they would be, but apparently not. Is there
any
> way I can tell R to regard them as integer vectors?
>
> Thanks.                                                    Faheem.
>
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http://www.R-project.org/posting-guide.html
>
-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595