Rblah in your example is a SEXP structure. Realloc is an interface to C
realloc and is not intended to resize SEXP structures -- it is used to
resize user-controlled memory (which is generally not created by
allocVector/INTEGER).
You would expect a call like:
int * val;
...
Realloc(val, 20, int);
Best,
Oleg
Charles Danko wrote:
> Hi,
>
> Trying to decrease the size of a SEXP variable without reassigning
> values individually in a loop.
>
> So far, I've tried using Realloc, as the follow source demonstrates:
> SEXP dothis() {
> SEXP Rblah;
> PROTECT(Rblah = NEW_INTEGER(6));
>
> int* blah = INTEGER(Rblah);
> blah[0] = 1;
> blah[1] = 2;
> blah[2] = 3;
>
> Realloc(Rblah, 3, INTEGER);
>
> UNPROTECT(1);
> return(Rblah);
> }
>
> According to the documentation, I think that this should work, however
> it returns an error on compile: "test.c:17: error: expected expression
> before ')' token" (line 17 refers to the Realloc line).
>
> Another solution that will suit my needs is managing the variable in C
> and assigning the pointer to an R type in the end. The following code
> gets at this, but int* and SEXP, INTEGER are incompatible:
> SEXP dothat() {
> int* blah = malloc(3);// = INTEGER(Rblah);
> blah[0] = 1;
> blah[1] = 2;
> blah[2] = 3;
>
> SEXP Rblah;
> PROTECT(Rblah = blah);
>
> UNPROTECT(1);
> return(Rblah);
> }
>
> Any suggestions for someone still new to SEXP memory management?
>
> Thanks,
> Charles
>
> ______________________________________________
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
--
Dr Oleg Sklyar * EBI-EMBL, Cambridge CB10 1SD, UK * +44-1223-494466
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