[R-sig-Geo] get() in raster ?

[Agustin Lobo]

Thanks Edzer, but neither work:
> v = list("r1","r2","r3")
> do.call(brick, v)
Error in .rasterObjectFromFile(x, objecttype = "RasterBrick", ...) :
  file: r1 does not exist
Calls: do.call ... <Anonymous> -> <Anonymous> -> .local -> .rasterObjectFromFile

> v = list(r1, r2, r3)
> bN = do.call(brick, v)
Error in .rasterObjectFromFile(x, objecttype = "RasterBrick", ...) :
  file: r1r2r3 does not exist
Calls: do.call ... <Anonymous> -> <Anonymous> -> .local -> .rasterObjectFromFile
In addition: Warning messages:
1: In if (x == "" | x == ".") { :
  the condition has length > 1 and only the first element will be used
2: In if (fileext %in% c(".GRD", ".GRI")) { :
  the condition has length > 1 and only the first element will be used
3: In if (!file.exists(x)) { :
  the condition has length > 1 and only the first element will be used
4: In if (file.exists(grdfile) & file.exists(grifile)) { :
  the condition has length > 1 and only the first element will be used

Also, in the real case the raster objects (i.e.,N1, N2 and N3) will
not have values in memory, so I'm not
positive that the list would be the way to go:

> class(N1)
[1] "RasterLayer"
attr(,"package")
[1] "raster"

> inMemory(N1)
[1] FALSE

> v = list(N1, N2, N3)
> bN = do.call(brick, v)
Error in as.matrix(getValues(r)) :
  error in evaluating the argument 'x' in selecting a method for
function 'as.matrix'
Calls: do.call ... <Anonymous> -> addLayer -> addLayer -> .local -> as.matrix

By now I'm editing the output of
paste("N",1:360,sep="")
for a call to brick() including the 360 raster objects. But there has
to be an elegant way of doing this. Not a critical issue though.

Agus

2010/11/20 Edzer Pebesma <edzer.pebesma at uni-muenster.de>:
> Just pushed "send" too fast -- try without quotes to pass the objects
> instead of their names:
>
> v = list(r1, r2, r3)
> do.call(brick, v)
>
>
> On 11/20/2010 11:51 AM, Agustin Lobo wrote:
>> ok, the problem is that, as noted by Carson,
>> I must use get("v") and not get(v).
>>
>> But still have problems to use get() within stack() or brick():
>>> r1 = raster(SM[,,1])
>>> r2 = raster(SM[,,2])
>>> r3 = raster(SM[,,3])
>>> v = c("r1","r2","r3")
>>> get("v")
>> [1] "r1" "r2" "r3"
>>> bSM = brick(get(v))
>> Error in .rasterObjectFromFile(x, objecttype = "RasterBrick", ...) :
>>   file: r1r2r3 does not exist
>> Calls: brick -> brick -> .local -> .rasterObjectFromFile
>>
>> ( I'm trying to use get() because have to
>> create a brick with 360 files that have been read as raster objects within
>> a loop using assign() )
>>
>> Agus
>>
>>
>> 2010/11/19 Robert J. Hijmans <r.hijmans at gmail.com>:
>>> This suggest that you have an object "r1" that is a Raster* object.
>>> Perhaps because of a saved session?
>>> Have you looked at
>>> ls()
>>> Robert
>>>
>>> On Fri, Nov 19, 2010 at 1:24 PM, Agustin Lobo <alobolistas at gmail.com> wrote:
>>>> Hi again!
>>>>
>>>> I'm having problems because cannot use get()  from base once package
>>>> raster has been installed:
>>>>
>>>>> v = c("r1","r2","r3")
>>>>> v
>>>> [1] "r1" "r2" "r3"
>>>>> get(v)
>>>> Loading required package: raster
>>>> Loading required package: sp
>>>> raster version 1.6-22 (17-November-2010)
>>>> class       : RasterLayer
>>>> nrow        : 18
>>>> ncol        : 36
>>>> ncell       : 648
>>>> projection  : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
>>>> xmin        : -180
>>>> xmax        : 180
>>>> ymin        : -90
>>>> ymax        : 90
>>>> xres        : 10
>>>> yres        : 10
>>>>
>>>> Even not having loaded raster, it gets automatically loaded once I
>>>> call get(). Is this a bug?
>>>> In general, is there a way to force that, in case of conflict, you run
>>>> a particular function from a given package?
>>>>
>>>> Thanks!
>>>>
>>>> Agus
>>>>
>>>
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>>>
>>
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>
> --
> Edzer Pebesma
> Institute for Geoinformatics (ifgi), University of Münster
> Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
> 8333081, Fax: +49 251 8339763  http://ifgi.uni-muenster.de
> http://www.52north.org/geostatistics      e.pebesma at wwu.de
>
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