On 10/06/11 14:57, Ben Zaitchik wrote:
Hello,
I have a large number of raster objects in memory, with names RH100,
RH101, RH102, etc. (myobjects <- ls(pattern='^RH')).
These rasters are sections of a continuous map, and I would like to
combine them using the RasterObject merge tool in package 'raster.'
Merge expects an input list of raster objects (outmap<-merge(x, y,
...), where x, y, and ... are raster objects). I can run the command
successfully if I type in every raster object that I want to merge,
but this is impractical for the large number of objects I'm combining.
I would like to apply merge to a list of object names defined using
some kind of wildcard-based list command, but I'm struggling to find
the right data types in R.
Is there some way to convert a vector of strings (e.g.,
as.vector(ls(pattern='^RH'))) to a vector of object names (as.names??)
that could be specified as the input to the merge function? What I'd
really like to do is something like outmap<-merge(myobjects[1:40]), in
order to merge the 40 raster objects, but I recognize that it might
not be so simple.
Advance apologies if this is already dealt with on the help list . . .
I've gone in circles on wildcard, lapply, and names threads and
haven't managed to get anything to work.
I think that
outmap <- do.call(merge,myobjects)
should work for you.
cheers,
Rolf Turner
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