[R-sig-Geo] Spatial3dArray - coordinates method

[Edzer Pebesma]

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
>
> _______________________________________________
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> R-sig-Geo at stat.math.ethz.ch
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>   

-- 
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