Dynamic list creation (SEXP in C) returns error "unimplemented type (29) in 'duplicate'"

George,

I don't see the relevance of the stackoverflow post you linked. In the
post, the author wanted to change the length of an existing "mother list"
(matrix, etc), while you specifically state that the length of L1 will not
change.

You say that the child lists (vectors if they are INTSXP/REALSXP) are
variable, but that is not what the linked post was about unless I am
completely missing something.

I can't really say more without knowing the details of how the vectors are
being created and why they cannot just have the right length from the start.

As for the error, that is a weird one. I imagine it means that a SEXP
thinks that it has a type other than ones defined in Rinternals. I can't
speak to how that could have happened from what you posted though.

Sorry I can't be of more help,
~G



On Mon, Nov 4, 2013 at 8:00 PM, George Vega Yon <g.vegayon at gmail.com> wrote:

Dear R-devel,

A couple of weeks ago I started to use the R C API for package
development. Without knowing much about C, I've been able to write
some routines sucessfully... until now.

My problem consists in dynamically creating a list ("L1") of lists
using .Call, the tricky part is that each element of the "mother list"
contains two vectors (INTSXP and REALEXP types) with varying sizes;
sizes that I set while I'm looping over another list's ("L1") elements
  (input list). The steps I've follow are:

FIRST: Create the "mother list" of size "n=length(L0)" (doesn't
change) and protect it as
   PROTECT(L1=allocVector(VECEXP, length(L0)))
and filling it with vectors of length two:
   for(i=0;i<n;i++) SET_VECTOR_ELT(L1,i, allocVector(VECSXP, 2));

then, for each element of the mother list:

   for(i=0;i<n;i++) {

SECOND: By reading this post in Stackoverflow

http://stackoverflow.com/questions/7458364/growing-an-r-matrix-inside-a-c-loop/7458516#7458516
I understood that it was necesary to (1) create the "child lists" and
protecting them with PROTECT_WITH_INDEX, and (2) changing its size
using SETLENGTH (Rf_lengthgets) and REPROTECT ing the lists in order
to tell the GC that the vectors had change.

THIRD: Once my two vectors are done ("id" and "lambda"), assign them
to the i-th element of the "mother list" L1 using
   SET_VECTOR_ELT(VECTOR_ELT(L1,i), 0, duplicate(id));
   SET_VECTOR_ELT(VECTOR_ELT(L1,i), 1, duplicate(lambda));

and unprotecting the elements protected with index: UNPROTECT(2);

}

FOURTH: Unprotecting the "mother list" (L1) and return it to R

With small datasets this works fine, but after trying with bigger ones
R (my code) keeps failing and returning a strange error that I haven't
been able to identify (or find in the web)

   "unimplemented type (29) in 'duplicate'"

This happens right after I try to use the returned list from my
routine (trying to print it or building a data-frame).

Does anyone have an idea of what am I doing wrong?

Best regards,

PS: I didn't wanted to copy the entire function... but if you need it
I can do it.

George Vega Yon
+56 9 7 647 2552
http://ggvega.cl