[Rcpp-devel] Efficient DataFrame access by row & column

Ken Williams Ken.Williams at windlogics.com
Wed Feb 20 00:19:52 CET 2013

> -----Original Message-----
> From: Yan Zhou [mailto:zhouyan at me.com]
> Sent: Tuesday, February 19, 2013 5:10 PM
> To: Dirk Eddelbuettel
> Cc: Ken Williams; rcpp-devel at lists.r-forge.r-project.org
> Subject: Re: [Rcpp-devel] Efficient DataFrame access by row & column
> The most inefficient part I see is the creation of a new NumericVector inside
> the inner most loop. You copied each column n times, of which n-1 times are
> unnecessary.

That's what I suspected.  So is there no way to access elements of a DataFrame without copying columns to a new vector first?



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