Another thing worth thinking about: perhaps the easiest way to side-step the issue is to work with a NumericMatrix rather than a DataFrame. At least, from the example you gave, it sounds like a container where you have the expectation that each column is a NumericVector of equal length.
If you can make the switch to NumericMatrix, then you can generate and operate with row/column views, e.g. NumericMatrix::Row and NumericMatrix::Column, which will generate references to rows / columns and hence avoid copying. (These are generated whenever you do e.g. x(i, _) or x(_, i) on a NumericMatrix x). -Kevin On Tue, Feb 19, 2013 at 3:26 PM, Ken Williams <ken.willi...@windlogics.com>wrote: > > > > From: John Merrill [mailto:john.merr...@gmail.com] > > Sent: Tuesday, February 19, 2013 5:24 PM > > To: Ken Williams > > Cc: Yan Zhou; Dirk Eddelbuettel; rcpp-devel@lists.r-forge.r-project.org > > Subject: Re: [Rcpp-devel] Efficient DataFrame access by row & column > > > > I'm a little puzzled by your question. Could you use a reference > instead of instantiating a new copy? > > I would love to use a reference, but I don't know how. That's in fact the > essence of my question. =) > > Is there already some example code somewhere showing how to get reference > to a DataFrame column without copying? I must be just missing it. > > -Ken > > > ________________________________ > > CONFIDENTIALITY NOTICE: This e-mail message is for the sole use of the > intended recipient(s) and may contain confidential and privileged > information. Any unauthorized review, use, disclosure or distribution of > any kind is strictly prohibited. If you are not the intended recipient, > please contact the sender via reply e-mail and destroy all copies of the > original message. Thank you. > _______________________________________________ > Rcpp-devel mailing list > Rcpp-devel@lists.r-forge.r-project.org > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel >
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