[R-sig-Geo] Spatial3dArray - coordinates method

[Michael Sumner]

Wow, this is great - I was thinking about this just yesterday.

Torleif: do you have an opinion on which NetCDF path is the most
useful for R with sp? RNetCDF or ncdf? GDAL is workable but takes
extra effort to build and then reconstruct 3d/4d from 2d bands. (I use
Windows mostly)

I use the RNetCDF package a lot, mainly because that's the one I
learnt to use first - there are binaries for Windows. It has some
problems in terms of R-style but they could be easily fixed.

Regards, Mike.

On Fri, Nov 20, 2009 at 12:26 AM, Edzer Pebesma
<edzer.pebesma at uni-muenster.de> wrote:
> No problems; sp in csv now has this, the next release will have it.
>
> Torleif Markussen Lunde wrote:
>> Hi
>>
>> To read netcdf data (or any other "gridded" spatial time data) I find it
>> convenient to define new classes Spatial3dArray and Spatial4dArray.
>>
>>  setClass("Spatial3dArray",
>>         representation("Spatial", data = "array", coords = "list",
>>                         time = "character", btime = "character"),
>>         prototype= list(data = array(NA, c(1,1,1,1)),
>>                         bbox=matrix(NA),
>>                         proj4string = CRS(as.character(NA)),
>>                         coords = list(1,1),
>>                         time = "posix",
>>                         btime = "posix"))
>>
>>
>> ##########################################
>> ###################EXAMPLE##################
>> ##########################################
>>
>> x <- matrix(seq(-10, 10, length = 100), 100, 100,
>>           byrow = FALSE)
>> y <- matrix(seq(-10, 10, length = 100), 100, 100,
>>           byrow = TRUE)
>>
>> tm <- 1:10
>> tm.c <- as.character(seq(as.POSIXct("2002-01-01 06:00:00",
>>                                   "2002-01-01 15:00:00"),
>>                         by="hours",
>>                         length.out=10))
>>
>> z <- array(NA, c(dim(x)[1], dim(x)[2], length(tm.c), 1))
>>
>> for (i in 1:10) {
>> z[,,i,] <- i * ( sin(sqrt(x^2+y^2)))
>> }
>>
>> sin3dA <- new("Spatial3dArray",
>>       data = z,
>>       coords = list(x, y),
>>       bbox = matrix(c(min(x), min(y), max(x), max(y), 2, 2), 2, 2,
>>       dimnames = list(NULL, c("min","max"))),
>>       time = tm.c,
>>       btime = c(min(tm.c), max(tm.c)))
>>
>> dimnames(slot(sin3dA, "data")) = list(NULL,
>>                                     NULL,
>>                                     slot(sin3dA, "time"),
>>                                     c("a"))
>> names(slot(sin3dA, "coords")) <- c("x", "y")
>>
>>
>> ##########################################
>>
>> for the coordinates method I would like to have two options on how to return
>> the coordinates; "list" or default "sp":
>>
>> coordinates.3dArray <- function (obj, type = "sp") {
>>       lat <- slot(obj, "coords")[[1]]
>>       long <- slot(obj, "coords")[[2]]
>>       if (type == "list") {
>>               return(list(long=long, lat=lat))
>>       } else if (type == "sp") {
>>               res <- as.matrix(cbind(c(long), c(lat)))
>>               dimnames(res) <- list(NULL, c("x1", "x2"))
>>       }
>> }
>> setMethod("coordinates", signature("Spatial3dArray"), coordinates.3dArray)
>>
>> This means that the default coordinates method in sp has to include the option
>> "..." . Would it be possible to include this in a future release of sp?
>>
>> The reason I want to keep the list option is to use a matrix oriented approach
>> in spplot, overlay, etc. methods. I also feel having a matrix/array approach
>> with these kind of data makes sense. Allowing type = "sp" means overlay() will
>> work more or less out of the box (however I would like to return a matrix),
>> and still I could get the list/matrix when desired.
>>
>>
>> Best wishes
>> Torleif Markussen Lunde
>> Centre for International Health
>> Bjerknes Centre for Climate Research
>> University of Bergen
>> Norway
>>
>> _______________________________________________
>> R-sig-Geo mailing list
>> R-sig-Geo at stat.math.ethz.ch
>> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>>
>
> --
> 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.springer.com/978-0-387-78170-9 e.pebesma at wwu.de
>
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