[R-sig-Geo] raster: stackApply problems..

[Ben Tupper]

Hi,

That is certainly is unexpected to have two different naming styles.
It's not really solution to take to the bank, but you could simply
compose your own names assuming that the layer orders are always
returned in ascending index order.
Would that work for you

### start
library(raster)

# Compute layer names for stackApply output
#
# @param index numeric, 1-based layer indices used for stackApply function
# @param prefix character, prefix for names
# @return character layers names in index order
layer_names <- function(index = c(2,2,3,3,1,1), prefix = c("layer.",
"index_")[1]){
  paste0(prefix, sort(unique(index)))
}

indices <- c(2,2,3,3,1,1)

r <- raster()
values(r) <- 1
# simple sequential stack from 1 to 6 in all cells
s <- stack(r, r*2, r*3, r*4, r*5, r*6)
s

beginCluster(2)
res <- clusterR(s, stackApply, args = list(indices=indices, fun = mean))
raster::endCluster()
names(res) <- layer_names(indices, prefix = "foobar.")
res

res2 <- stackApply(s, indices, mean)
names(res2) <- layer_names(indices, prefix = "foobar.")
res2
### end


On Wed, Nov 20, 2019 at 1:36 AM Leonidas Liakos via R-sig-Geo
<r-sig-geo using r-project.org> wrote:
>
> This is not a reasonable solution. It is not efficient to run stackapply
> twice to get the right names. Each execution can take hours.
>
>
> Στις 20/11/2019 3:30 π.μ., ο Frederico Faleiro έγραψε:
> > Hi Leonidas,
> >
> > both results are in the same order, but the name is different.
> > You can rename the first as in the second:
> > names(res) <- names(res2)
> >
> > I provided an example to help you understand the logic.
> >
> > library(raster)
> > beginCluster(2)
> > r <- raster()
> > values(r) <- 1
> > # simple sequential stack from 1 to 6 in all cells
> > s <- stack(r, r*2, r*3, r*4, r*5, r*6)
> > s
> > res <- clusterR(s, stackApply, args = list(indices=c(2,2,3,3,1,1), fun =
> > mean))
> > res
> > res2 <- stackApply(s, c(2,2,3,3,1,1), mean)
> > res2
> > dif <- res - res2
> > # exatly the same order because the difference is zero for all layers
> > dif
> > # rename
> > names(res) <- names(res2)
> >
> > Best regards,
> >
> > Frederico Faleiro
> >
> > On Tue, Nov 19, 2019 at 4:15 PM Leonidas Liakos via R-sig-Geo <
> > r-sig-geo using r-project.org> wrote:
> >
> >> I run the example with clusterR:
> >>
> >> no_cores <- parallel::detectCores() -1
> >> raster::beginCluster(no_cores)
> >> ?????? res <- raster::clusterR(inp, raster::stackApply, args =
> >> list(indices=c(2,2,3,3,1,1),fun = mean))
> >> raster::endCluster()
> >>
> >> And the result is:
> >>
> >>> res
> >> class?????????? : RasterBrick
> >> dimensions : 180, 360, 64800, 3?? (nrow, ncol, ncell, nlayers)
> >> resolution : 1, 1?? (x, y)
> >> extent???????? : -180, 180, -90, 90?? (xmin, xmax, ymin, ymax)
> >> crs?????????????? : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
> >> source???????? : memory
> >> names?????????? : layer.1, layer.2, layer.3
> >> min values :???????? 1.5,???????? 3.5,???????? 5.5
> >> max values :???????? 1.5,???????? 3.5,???????? 5.5??
> >>
> >>
> >> layer.1, layer.2, layer.3 (?)
> >>
> >> So what corrensponds to what?
> >>
> >>
> >> If I run:
> >>
> >> res2 <- stackApply(inp,c(2,2,3,3,1,1),mean)
> >>
> >> The result is:
> >>
> >>> res2
> >> class      : RasterBrick
> >> dimensions : 180, 360, 64800, 3  (nrow, ncol, ncell, nlayers)
> >> resolution : 1, 1  (x, y)
> >> extent     : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
> >> crs        : +proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0
> >> source     : memory
> >> names      : index_2, index_3, index_1
> >> min values :     1.5,     3.5,     5.5
> >> max values :     1.5,     3.5,     5.5
> >>
> >> There is no consistency with the names of the output and obscure
> >> correspondence with the indices in the case of clusterR
> >>
> >>
> >>         [[alternative HTML version deleted]]
> >>
> >> _______________________________________________
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> >> R-sig-Geo using r-project.org
> >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
> >>
> >
>
>
> --
> Λιάκος Λεωνίδας, Γεωγράφος
> https://www.geographer.gr
> PGP fingerprint: 5237 83F8 E46C D91A 9FBB C7E7 F943 C9B6 8231 0937
>
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-- 
Ben Tupper
Bigelow Laboratory for Ocean Science
West Boothbay Harbor, Maine
http://www.bigelow.org/
https://eco.bigelow.org