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"gridded<-" = function(obj, value) {
if (is(obj, "Spatial"))
p4s = proj4string(obj)
else
p4s = as.character(NA)
if (is.logical(value)) {
if (is(obj, "SpatialPixelsDataFrame") || is(obj, "SpatialGridDataFrame")) {
if (!value)
obj = as(obj, "SpatialPointsDataFrame")
} else if (is(obj, "SpatialPixels")) {
if (!value)
obj = as(obj, "SpatialPoints")
} else if (is(obj, "SpatialPointsDataFrame")) {
if (value)
obj = SpatialPixelsDataFrame(obj, obj@data)
} else if (is(obj, "SpatialPoints")) {
if (value)
#obj = as(obj, "SpatialGrid")
obj = SpatialPixels(obj)
} else
stop("gridded<- only works for SpatialPoints[DataFrame] or SpatialGrid[DataFrame]")
} else {
if (is(value, "formula") || is(value, "character")) {
if (!is(obj, "data.frame"))
stop("data.frame expected as object")
coordinates(obj) = value
gridded(obj) = TRUE
} else if (is(value, "GridTopology"))
return(SpatialGridDataFrame(grid = SpatialGrid(grid = value), data.frame(obj)))
else
stop(paste("cannot deal with value of class"), class(value))
# further deal with more complex forms of value
}
proj4string(obj) = CRS(p4s)
obj
}
setAs("SpatialPoints", "SpatialPixels", function(from) {
gridded(from) <- TRUE
from
})
setAs("SpatialPointsDataFrame", "SpatialPixelsDataFrame", function(from) {
gridded(from) <- TRUE
from
})
setMethod("gridded", "Spatial", function(obj) is(obj, "SpatialPixels"))
fullgrid = function(obj) return(is(obj, "SpatialGrid"))
"fullgrid<-" = function(obj, value) {
p4s = proj4string(obj)
if (!is(obj, "SpatialPixels"))
stop("fullgrid<- only works on objects of class or extending SpatialPixels")
if (fullgrid(obj) != value) { # convert:
if (value) { # convert to full grid
if (is(obj, "SpatialPixelsDataFrame"))
obj = as(obj, "SpatialGridDataFrame")
else
obj = as(obj, "SpatialGrid")
} else { # convert to Pixels
if (is(obj, "SpatialGridDataFrame"))
obj = as(obj, "SpatialPixelsDataFrame")
else
obj = as(obj, "SpatialPixels")
}
}
proj4string(obj) = CRS(p4s)
obj
}
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