[R-sig-Geo] raster: apply() in brick objects?

[Agustin Lobo]

...well, it's Friday...

it's actually just
> brmax <- calc(br,max,na.rm=T)
> show(brmax)
class       : RasterBrick
filename    :
nlayers     : 1
nrow        : 5
ncol        : 5
ncell       : 25
projection  : NA
min value   : 248
max value   : 248
extent      : 0, 1, 0, 1  (xmin, xmax, ymin, ymax)
resolution  : 0.2, 0.2  (x, y)

that simple.

Agus

2010/11/26 Agustin Lobo <alobolistas at gmail.com>:
> Hi!
>
> Given a brick object (longitude, latitude, time), I need a (lon,lat)
> layer with the maximum value of each cell across time.
> That's  the equivalent to
>> x = array(round(runif(n=3*4*5,min=0,max=10)),dim=c(3,4,5))
>> apply(x,c(1,2),max,na.rm=T)
>
> but for x being a brick object. How can I do it with raster?
>
> I've tried
>
>> funmax <- function(x) {apply(x,c(1,2),max,na.rm=T)}
>> show(br)
> class       : RasterBrick
> filename    :
> nlayers     : 3
> nrow        : 5
> ncol        : 5
> ncell       : 25
> projection  : NA
> min value   : ? ? ?
> max value   : ? ? ?
> extent      : 0, 1, 0, 1  (xmin, xmax, ymin, ymax)
> resolution  : 0.2, 0.2  (x, y)
>> brmax <- calc(br,funmax)
>
> But the result is wrong, as it should be 1 layer and not 3:
>> show(brmax)
> class       : RasterBrick
> filename    :
> nlayers     : 3
> nrow        : 5
> ncol        : 5
> ncell       : 25
> projection  : NA
> min value   : 232 232 248
> max value   : 248 248 248
> extent      : 0, 1, 0, 1  (xmin, xmax, ymin, ymax)
> resolution  : 0.2, 0.2  (x, y)
>
> I've also tried with stackApply(), but do not think that's the way to go.
> Also, I'm concerned that apply() is typically very slow in R, and I'm
> dealing with a large brick object.
>
> Thanks
>
> Agus
>