[R-sig-Geo] subseting an spatial polygons data frame

[Agustin Lobo]

I want to discard few polygons from an
sp. poly. DF. I'm trying things such as:
 > str(x,max.level=2)
Formal class 'SpatialPolygonsDataFrame' [package "sp"] with 5 slots
   ..@ data       :'data.frame':	42 obs. of  9 variables:
   ..@ polygons   :List of 42
   ..@ plotOrder  : int [1:42] 32 35 38 1 8 29 33 26 27 31 ...
   ..@ bbox       : num [1:2, 1:2] 437951 4605986 459732 4633538
   .. ..- attr(*, "dimnames")=List of 2
   ..@ proj4string:Formal class 'CRS' [package "sp"] with 1 slots
 >
 > x <- subset(x,row.names(x)!="1")
Error in `[.data.frame`(x at data, i, j, ..., drop = FALSE) :
   undefined columns selected

but the output of row.names(x)!="1"
is correct, what am I doing wrong?  Is subset() (from maptools) not 
appropriate for objects of type  SPDF ?

Thanks

Agus