[R-sig-Geo] calc, overlay and raster stacks

[Agustin Lobo]

Thanks!

It works with raster_1.6-22 and  sp_0.9-72

The last 2 lines must be
fun1 <- function(x,y) { x[y!=248 & y!=232] <- NA; return(x)}
rc <- overlay(rNDVI, rSM, fun=fun1)

Is it required to include datatype and/or format in overlay() to get
the result (rc) written to disk
and not fully loaded in RAM?

Agus

2010/11/19 Robert J. Hijmans <r.hijmans at gmail.com>:
> Hi Agus,
>
> Your example with overlay works for me. I think you need to update
> 'raster' . In earlier versions many functions only worked for
> RasterLayer objects, now most functions also support multi-layer
> (RasterStack or RasterBrick) objects.
>
> Robert
>
> On Fri, Nov 19, 2010 at 8:50 AM, Agustin Lobo <alobolistas at gmail.com> wrote:
>> Hi!
>>
>> I have to set as NA data in a 3D array (time series of images)
>> according to values in another 3D array of Quality flags
>>
>> #Example
>> NDVI = round(array(rnorm(5*5*3,180,10),dim=c(5,5,3)))
>> SM = array(rep(248,5*5*3),dim=c(5,5,3))
>> SM[4,3:4,1:2] = 232
>> SM[2,3:4,1:2] = 243
>> SM[3,4,1:2] = 243
>>
>> #The only valid data are the ones for which SM is either 232 or 248, so:
>> NDVI[SM!=248] <- NA
>> NDVI[SM!=232] <- NA
>> #which is the same as
>> NDVI[SM!=248 & SM!=232] <- NA
>>
>> #The problem is that what I really have are images 3697 columns x
>> 1905 rows and 360 Bands (and even larger) , so I try package raster
>>
>> require(rgdal)
>> require(raster)
>>
>> #First, I make fake data:
>> rNDVI = stack(raster(NDVI[,,1]),raster(NDVI[,,2]),raster(NDVI[,,2]))
>> rSM = stack(raster(SM[,,1]),raster(SM[,,2]),raster(SM[,,2]))
>>
>> fun <- function(x,y) { x[y!=248 & y!=232] <- NA; return(x)}
>>> rc <- overlay(rNDVI, rSM, fun)
>> Error in function (classes, fdef, mtable)  :
>>  unable to find an inherited method for function "overlay", for
>> signature "RasterStack", "RasterStack"
>> Calls: overlay -> <Anonymous>
>>
>> #It seems that calc() must be used for stacks, but seems to me that calc()
>> #only accepts one stack, not two. Maybe I should just stack both NDVI and SM?
>>
>> Thanks!
>> Agus
>>
>
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