Thanks, David. That does, indeed, work. It didn't occur to me that a list would
do the job as an argument.
Thanks for the fix!
kevin
On Nov 16, 2010, at 6:58 PM, David Winsemius wrote:
>
> 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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