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

[Tim Keitt]

Yup, that example is really helpful. Note that if you do:

  the_list.attr("row.names") = IntegerVector::create(NA_INTEGER, -nrow);

it will create implicit row names from 1:nrow. The number of rows must be
negative.

THK


On Sun, Jun 8, 2014 at 8:03 PM, Dmitry Nesterov <dmitry.nesterov at gmail.com>
wrote:

> 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
>
> _______________________________________________
> Rcpp-devel mailing list
> Rcpp-devel at lists.r-forge.r-project.org
> https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
>



-- 
http://www.keittlab.org/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.r-forge.r-project.org/pipermail/rcpp-devel/attachments/20140609/91ee968b/attachment-0001.html>