On Nov 16, 2010, at 1:04 PM, Kevin Ummel wrote:
Sorry, I shouldn't have used 'sum' as an example; I am looking for a
solution in the case of functions that do not result in simple
vectors or matrices.
The "real-world" example is something like the following using the
'raster' package, though (I think) any command producing an S4
object could be a candidate:
r1 <- raster(system.file("external/test.grd", package="raster"))*1
r2 <- raster(system.file("external/test.grd", package="raster"))*2
obs=objects(pattern=glob2rx("r?"))
#Would like to generate the equivalent of...
stack(r1,r2)
Have you tried what would seem to be the obvious generalization of the
example offered:
str(stack(sapply(obs, get))) # it does not throw any error and seems
to have data in it
...using a variation of obs as an argument to 'stack' (potentially
very long).
Also tested:
str(
stack( c(sapply(obs, get),sapply(obs, get)) ) # doing a four object
test
) # no error
(I did not see any indication in the help page for get that it's
operation was restricted to S3 objects. If there is such a restriction
then warnings should be added there.)
Cheers,
Kevin
On Nov 16, 2010, at 5:07 PM, David Winsemius wrote:
On Nov 16, 2010, at 10:34 AM, Kevin Ummel wrote:
A bit embarrassed to post this seemingly trivial question, but I
can't find anything in the archive that's quite relevant:
a1=1
a2=2
obs=objects(pattern=glob2rx("a?"))
I want to utilize 'obs' as a function argument to produce
something like:
sum(a1,a2)
?get
sum(sapply(obs, get))
[1] 3
Obviously, sum(obs) doesn't work, but I've tried variations of
'eval', 'parse', 'mget', and 'noquote' without success. What am I
missing?
Thanks,
Kevin
--
David Winsemius, MD
West Hartford, CT
David Winsemius, MD
West Hartford, CT
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