[Rcpp-devel] RcppEigen: Getting and setting dimnames of sparse matrix

[Douglas Bates]

On Sat, Jan 19, 2013 at 10:38 AM, Douglas Bates <bates at stat.wisc.edu> wrote:

>
On thinking about this a bit more, the dimnames should be cloned before
being assigned, otherwise you end up with two references to the same
storage.  And once you try to clone you get into the SlotProxy area where
you need to know what you are cloning.  One way of doing this is shown in
the enclosed.  An alternative is

Xout.slot("Dimnames") = clone(as<SEXP>((Xin.slot("Dimnames"))));
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> library(Matrix)
Loading required package: lattice
> library(RcppEigen)
Loading required package: Rcpp
> library(inline)
> 
> 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 .
> str(ugM)
Formal class 'dgCMatrix' [package "Matrix"] with 6 slots
  ..@ i       : int [1:4] 1 0 2 1
  ..@ p       : int [1:4] 0 1 3 4
  ..@ Dim     : int [1:2] 3 3
  ..@ Dimnames:List of 2
  .. ..$ : chr [1:3] "a" "b" "c"
  .. ..$ : chr [1:3] "a" "b" "c"
  ..@ x       : num [1:4] 1 1 1 1
  ..@ factors : list()
> 
> src <- '
+ typedef Eigen::SparseMatrix<double> SpMat;
+ S4    Xin(XX_);
+ SpMat X(as<SpMat>(XX_));
+ S4    Xout(wrap(X));
+ Xout.slot("Dimnames") = clone(List(Xin.slot("Dimnames")));
+ return(Xout);
+ '
> 
> names_ <- cxxfunction(signature(XX_="dsCMatrix"), plugin="RcppEigen",
+         body=src)
> 
> names_(ugM)
3 x 3 sparse Matrix of class "dgCMatrix"
  a b c
a . 1 .
b 1 . 1
c . 1 .
> 
> 
> proc.time()
   user  system elapsed 
 10.392   0.496  10.918