[R] merge large number of raster objects

[Henrik Bengtsson]

See ?get and ?do.call.  That should be enough.

?Reduce may be an alternative for do.call(), but could also be less
memory efficient.

My $.02

/Henrik

On Thu, Jun 9, 2011 at 7:57 PM, Ben Zaitchik <zaitchik at jhu.edu> 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.
>
> Thank you,
> Ben
>
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