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

[Leonidas Liakos]

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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>>
> 


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Λιάκος Λεωνίδας, Γεωγράφος
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