[Rcpp-devel] RcppEigen: Getting and setting dimnames of sparse matrix
Dirk Eddelbuettel
edd at debian.org
Sat Jan 19 15:26:33 CET 2013
Hi Søren,
On 19 January 2013 at 08:45, Søren Højsgaard wrote:
| Dear Dirk
|
| Thanks for your reply. Seems to me that there is an attr() method for for setting and retrieving attributes - but this is not available for sparse matrices. For sparse matrices there seems to be a slot() method that will retrieve but not set slots?
As I said in my message below, sparse matrices are S4 object so this may well
be different. Did you try to set a slot value?
I also said that I don't work all that much with S4 in R (or Rcpp) but other
readers do so maybe someone has a trick. I just glanced at S4.h which leads
you to SlotProxy in RObject.h, and looking at runit.S4.R also suggests it may
work.
Regards, Dirk
| Regards
| Søren
|
| -----Original Message-----
| From: Dirk Eddelbuettel [mailto:edd at debian.org]
| Sent: 19. januar 2013 00:18
| To: Søren Højsgaard
| Cc: rcpp-devel at lists.r-forge.r-project.org
| Subject: Re: [Rcpp-devel] RcppEigen: Getting and setting dimnames of sparse matrix
|
|
| Hi Søren,
|
| On 18 January 2013 at 23:07, Søren Højsgaard wrote:
| | Dear all,
| | I put a sparse "dgCMatrix" into RcppEigen code as a sparse matrix. In Rcpp I create a new matrix of same dimensions as the input matrix. I would like to copy the dimnames from the input matrix to the output matrix. Can this be done? (It is essential that I can stick to working with sparse matrices). I know that I can set the dimensions on the R-side, but that involves AFAIK copying the object which takes time.
|
| "It should".
|
| I have not worked all that much with sparse matrices, but dimnames etc are merely attributes at the R level. And we read and write these just as easily at the C++ level.
|
| Have a look at few of the recent posts at http://gallery.rcpp.org
| in particular
|
| http://gallery.rcpp.org/articles/getting-attributes-for-xts-example
|
| and
|
| http://gallery.rcpp.org/articles/creating-xts-from-c%2B%2B
|
| where I, respectively, "get" and "set" the attributes that make an xts
| object: dimnames, an index (itself with class and time zone attributes) and timezone and class info.
|
| For sparse matrices the mechanics may be slighty different due to the S4-ness of things but the rest should work. I put a feeble attempt at working with sparse matrices here:
|
| http://gallery.rcpp.org/articles/armadillo-sparse-matrix/
|
| Maybe we can do something similar with richer 'matrix factory' functions for Eigen?
|
| Dirk
|
| |
| | Example:
| |
| | src<-'
| | using namespace Rcpp;
| | typedef Eigen::SparseMatrix<double> SpMat;
| | SpMat X(as<SpMat>(XX_));
| | return(wrap(X));
| | '
| |
| | names_ <- cxxfunction(signature(XX_="matrix"), plugin="RcppEigen",
| | body=src)
| |
| | ugM <- new("dgCMatrix"
| | , i = c(1L, 0L, 2L, 1L)
| | , p = c(0L, 1L, 3L, 4L)
| | , Dim = c(3L, 3L)
| | , Dimnames = list(c("a", "b", "c"), c("a", "b", "c"))
| | , x = c(1, 1, 1, 1)
| | , factors = list())
| |
| | > ugM
| | 3 x 3 sparse Matrix of class "dgCMatrix"
| | a b c
| | a . 1 .
| | b 1 . 1
| | c . 1 .
| | >
| | > names_(ugM)
| | 3 x 3 sparse Matrix of class "dgCMatrix"
| |
| | [1,] . 1 .
| | [2,] 1 . 1
| | [3,] . 1 .
| |
| | Any advice? Thanks in advance
| | Søren
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|
| --
| Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com
--
Dirk Eddelbuettel | edd at debian.org | http://dirk.eddelbuettel.com
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