>>>>> Henrik Bengtsson <h...@biostat.ucsf.edu> >>>>> on Mon, 31 Jan 2011 11:16:59 -0800 writes:
> Hi, str() on raster objects fails for certain dimensions. For > example: >> str(as.raster(0, nrow=1, ncol=100)) 'raster' chr [1, 1:100] > "#000000" "#000000" "#000000" "#000000" ... >> str(as.raster(0, nrow=1, ncol=101)) Error in `[.raster`(object, > seq_len(max.len)) : subscript out of bounds > This seems to do with how str() and "[.raster"() is coded; when > subsetting as a vector, which str() relies on, "[.raster"() > still returns a matrix-like object, e.g. >> img <- as.raster(1:25, max=25, nrow=5, ncol=5); >> img[1:2] > [,1] [,2] [,3] [,4] [,5] > [1,] "#0A0A0A" "#3D3D3D" "#707070" "#A3A3A3" "#D6D6D6" > [2,] "#141414" "#474747" "#7A7A7A" "#ADADAD" "#E0E0E0" > compare with: >> as.matrix(img)[1:2] > [1] "#0A0A0A" "#3D3D3D" > The easy but incomplete fix is to do: > str.raster <- function(object, ...) { > str(as.matrix(object), ...); > } > Other suggestions? The informal "raster" class is behaving ``illogical'' in the following sense: > r <- as.raster(0, nrow=1, ncol=11) > r[seq_along(r)] Error in `[.raster`(r, seq_along(r)) : subscript out of bounds or, here equivalently, > r[1:length(r)] Error in `[.raster`(r, 1:length(r)) : subscript out of bounds When classes do behave in such a way, they definitely need their own str() method. However, the bug really is in "[.raster": Currently, r[i] is equivalent to r[i,] which is not at all matrix-like and its help clearly says that subsetting should work as for matrices. A recent thread on R-help/R-devel has mentioned the fact that "[" methods for matrix-like methods need to use both nargs() and missing() and that "[.dataframe" has been the example to follow "forever", IIRC already in S and S-plus as of 20 years ago. Thank you, Henrik, for the bug report. Martin ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel