Spatial3dArray - coordinates method

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

--
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of M?nster
Weseler Stra?e 253, 48151 M?nster, 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