[R] 3D density estimation with library sm - no estimate returned

[Gregory Jefferis]

Dear List,

I have been trying to use library sm to do density estimation on a 3D
dataset.  I am using the current MacOS X binary of sm from CRAN.  If I do
this on a 2D dataset, sm.density returns a list including the component
"estimate" which contains the density estimate over a uniform grid.  When
doing this with 3D data, although I get a nice plot (even when I don't ask
for one), the returned list only contains the original data (see below).  It
would appear that the internal function sm.density.3d is returning NULL.
Have I misunderstood what should be returned?  Is this a platform specific
problem?  Can someone suggest a fix or an alternative library for my
application?  Very many thanks for your help,

Greg Jefferis.

> R.version
         _         
platform powerpc-apple-darwin7.9.0
arch     powerpc   
os       darwin7.9.0
system   powerpc, darwin7.9.0
status   Patched   
major    2         
minor    1.0       
year     2005      
month    05        
day      12        
language R

> library(sm)
> str(sm.density(matrix(rnorm(300),ncol=3),display="none"))
List of 2
 $ data:List of 3
  ..$ x    : num [1:100, 1:3]  0.9470 -1.5112  1.0589 -0.0884 -0.1900 ...
  .. ..- attr(*, "dimnames")=List of 2
  .. .. ..$ : NULL
  .. .. ..$ : chr [1:3] "" "" ""
  ..$ nbins: num 0
  ..$ freq : num [1:100] 1 1 1 1 1 1 1 1 1 1 ...
 $ call: language sm.density(x = matrix(rnorm(300), ncol = 3), display =
"none")
> str(sm.density(matrix(rnorm(200),ncol=2),display="none"))
List of 10
 $ eval.points: num [1:50, 1:2] -2.67 -2.57 -2.47 -2.38 -2.28 ...
  ..- attr(*, "dimnames")=List of 2
  .. ..$ : NULL
  .. ..$ : chr [1:2] "xnew" "ynew"
 $ estimate   : num [1:50, 1:50] 3.76e-05 5.10e-05 7.57e-05 1.22e-04
2.05e-04 ...
 $ h          : Named num [1:2] 0.414 0.512
  ..- attr(*, "names")= chr [1:2] "" ""
 $ h.weights  : num [1:100] 1 1 1 1 1 1 1 1 1 1 ...
 $ weights    : num [1:100] 1 1 1 1 1 1 1 1 1 1 ...
 $ se         : num [1:50, 1:50] 0.0306 0.0306 0.0306 0.0306 0.0306 ...
 $ upper      : num [1:50, 1:50] 0.00454 0.00468 0.00489 0.00523 0.00571 ...
 $ lower      : num [1:50, 1:50] 0 0 0 0 0 0 0 0 0 0 ...
 $ data       :List of 3
  ..$ x    : num [1:100, 1:2] -0.694 -0.192  0.149 -0.718 -0.357 ...
  .. ..- attr(*, "dimnames")=List of 2
  .. .. ..$ : NULL
  .. .. ..$ : chr [1:2] "" ""
  ..$ nbins: num 0
  ..$ freq : num [1:100] 1 1 1 1 1 1 1 1 1 1 ...
 $ call       : language sm.density(x = matrix(rnorm(200), ncol = 2),
display = "none")
> 



-- 
Gregory Jefferis, PhD                               and:
Research Fellow
Department of Zoology                               St John's College
Downing Street                                      Cambridge
Cambridge, CB2 3EJ                                  CB2 1TP

Tel: +44 (0)1223 336683                             +44 (0)1223 339899
Fax: +44 (0)1223 336676                             +44 (0)1223 337720

gsxej2 at cam.ac.uk