[Rd] append/concatenate an element to a list in C-language

Tony Plate tplate at acm.org
Fri Oct 19 04:07:05 CEST 2007

This sounds like it could be dangerous, but if you're sure it's 
necessary and you know what you are doing, you could investigate whether 
the "pairlist" internal structure might enable you to do this (AFAIK, a 
"pairlist" is a traditional linked-list data structure).  In general, 
pairlists seem to be used very little, and I've never seen their use 
encouraged, so I would be very cautious.  You can read more about 
"pairlists" under ?pairlist, in the R-internals manual, and in the 
source starting at src/include/Rinternals.h (look for "LISTSXP").

-- Tony Plate

Robert Castelo wrote:
> dear people,
> i need to code a function in C working in R and receives two R SEXP
> objects as parameters, where one is a list and another is a vector of
> integers:
> void f(SEXP list, SEXP vector) {
>   ...
>   return list;
> }
> and it should return the given list with the integer vector concatenated
> at the end (as the last element of the list). the list can be really big
> so i would not like to create a new list from scratch and copy all the
> elements, including the additional one. i'm also interested in knowing
> how should i properly handle protections of the SEXP objects when doing
> this.
> i've been looking at the R source code for everything that has to do
> with CAR, CDR, CONS, and even found functions with promising names like
> listAppend or GrowList but i have not been able to figure this out nor i
> haven't been able to find any reference on how to do this by googling
> all around, so any help will be very much appreciated.
> thanks a lot!!!
> robert.
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel

More information about the R-devel mailing list