[R] merge large number of raster objects

[Henrik Bengtsson]

...and ?mget for retrieving multiple objects as a list.  /Henrik

On Thu, Jun 9, 2011 at 10:32 PM, Henrik Bengtsson <hb at biostat.ucsf.edu> wrote:
> 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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>>
>