[Rcpp-devel] returning array from C

I think it's more useful to think of whether a limited subset of these 
operations will work for your application and whether you can convey the limits 
of the class to the user---I'd hate to convince a user that something _is_ a 
numeric vector and have them waste hours wondering why some piece of code is not 
working.

Thanks to everyone for your very helpful comments.

It seems clear there is no easy way to make an object "look like" a numeric vector to R unless it *is* a numeric vector.

From what I've seen the ff package comes close, but they have indeed reinvented all the necessary R functions (including a package 'ffbase' replicating some significant subset of R 'base')

It was clear from the start that the simplest and safest approach would be to copy the data to R (using Rcpp::wrap). The best alternative, it seems, might be to try converting the data into an ff object. But that's a can of worms which I will leave for another day.

Thanks once again to all those knowledgeable folks who so quickly provided the needed information.

Steve