[Rcpp-devel] Speed up of the data.frame creation in DataFrame.h

[Dmitry Nesterov]

Dirk,
The example that you provided in the link to the Rcpp Gallery has been very helpful.
Thank you for pointing it out, it did speed up my data frame creation code significantly.
It allows me to use Rcpp where I used C api and keep practically the same speed of execution.

Best, Dmitry
On Jun 8, 2014, at 6:42 PM, Dirk Eddelbuettel <edd at debian.org> wrote:

> 
> On 8 June 2014 at 13:33, Christian Gunning wrote:
> | Hello list, long time no see!
> 
> Indeed :)
> 
> | Dmitry,
> | Have you identified any other consequences than what Romain pointed
> | out?  This information would be useful for the rest of us.
> | 
> | Some key points that I agree with:
> |  * as per Dirk: this is a nice little piece of sleuthing.  Your
> | benchmarking shows that the effect is significant.
> |  * as per your comments: a key intent of Rcpp is allow the user the
> | freedom to acheive optimization and do their own error checking.
> |   * as per Romain: let's not break things.
> | 
> | It seems possible address all of these points, perhaps with a
> | dedicated function, as per your comments.  I can help with this, if
> | you're interested.
> 
> Also note the exisiting 'faster data.frame creation from lists' article at
> the Rcpp Gallery:
> 
>  http://gallery.rcpp.org/articles/faster-data-frame-creation/
> 
> I only looked at it briefly in this context, and it seems that some changes
> we made to Rcpp since this Gallery post was written make its suggestion a
> little less dramatic.  But I did not have time to dig deeper.
> 
> But your point two here is key:  Rcpp is a _framework_ and users are of
> course free to add little helper functions at their end -- and even
> encouraged to do so.  Not everything has to happen at the Rcpp side of things.
> 
> | Key question: what is the intended behavior of this function?  E.g.,
> | throw an exception on length mismatch?  My vote is for a limited
> | function that deals with a limited number of use cases and provides
> | reasonable error-checking (e.g. throws exception for input outside
> | scope), versus a logic-heavy function that handles recycling, for
> | example.  Does this match your use-case?
> 
> Good ideas.
> 
> Dirk
> 
> -- 
> http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org