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

[John Merrill]

I'm a little puzzled by your question.  Could you use a reference instead
of instantiating a new copy?


On Tue, Feb 19, 2013 at 3:19 PM, Ken Williams
<Ken.Williams at windlogics.com>wrote:

>
>
> > -----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?
>
>  -Ken
>
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