R/xyCell.R

In raster: Geographic Data Analysis and Modeling

# Author: Robert J. Hijmans
# Date :  October 2008
# Version 1.0
# Licence GPL v3

setMethod("yFromRow", signature(object="Raster", row="missing"), 
	function(object, row) {
		if (rotated(object)) {
			stop('this function is not supported for rotated rasters')
		}
		row=1:nrow(object)
		ymax(object) - ((row-0.5) * yres(object))
	}	
)


setMethod("yFromRow", signature(object="Raster", row="numeric"), 
	function(object, row) {
		if (rotated(object)) {
			stop('this function is not supported for rotated rasters')
		}
		row <- round(as.vector(row))
		row[row < 1 | row > object@nrows] <- NA
		ymax(object) - ((row-0.5) * yres(object))
	}	
)



.yFromRow <- function(object, rownr) {
	if (rotated(object)) {
		stop('this function is not supported for rotated rasters')
	}
	ymax(object) - ((rownr-0.5) * yres(object))
}	
	

setMethod("xFromCol", signature(object="Raster", col="numeric"), 
	function(object, col=1:ncol(object)) {
		if (rotated(object)) {
			stop('this function is not supported for rotated rasters')
		}
		col <- round(as.vector(col))
		col[col < 1 | col > object@ncols] <- NA
		xmin(object) + (col - 0.5) * xres(object) 
	}  
)

setMethod("xFromCol", signature(object="Raster", col="missing"), 
	function(object, col=1:ncol(object)) {
		if (rotated(object)) {
			stop('this function is not supported for rotated rasters')
		}
		col=1:ncol(object)
		xmin(object) + (col - 0.5) * xres(object) 
	}  
)

.xFromCol <- function(object, colnr) {
	if (rotated(object)) {
		stop('this function is not supported for rotated rasters')
	}
	xmin(object) + (colnr - 0.5) * xres(object) 
}  


setMethod("cellFromXY", signature(object="BasicRaster", xy="ANY"), 
	function(object, xy) {
		if (inherits(xy, 'SpatialPoints')) {
			xy <- coordinates(xy)[,1:2,drop=FALSE]
			x <- xy[,1]
			y <- xy[,2]
		} else if (is.null(dim(xy))) { 
			x <- xy[1]
			y <- xy[2] 
		} else { 
			x <- xy[,1]
			y <- xy[,2] 
		}

		if (rotated(object)) {
			cr <- object@rotation@transfun(xy, inv=TRUE)
			cell <- (cr[,2]-1) * object@ncols + cr[,1]
		} else {
			cell <- .doCellFromXY(
				object@ncols, object@nrows,
				object@extent@xmin, object@extent@xmax,
				object@extent@ymin, object@extent@ymax, 
				x, y)
		}
		return(cell)
	}
)

setMethod("colFromX", signature(object="BasicRaster", x="numeric"), 
	function ( object, x )	{
# from pre-generic
#		if (inherits(x, 'Spatial')) { 
#			x <- x@coords[,1] 
#		}
		if (rotated(object)) {
			stop('this function is not supported for rotated rasters')
		}
		colnr <- trunc((x - xmin(object)) / xres(object)) + 1 
		colnr[ x == xmax(object) ] <- object@ncols
		colnr[ x < xmin(object) | x > xmax(object) ] <- NA
		return(as.vector(colnr))
	}
)


setMethod("rowFromY", signature(object="BasicRaster", y="numeric"), 
	function(object, y)	{
# from pre-generic
#		if (inherits(y, 'Spatial')) {
#			y <- y@coords[,2] 
#		}
		if (rotated(object)) {
			stop('this function is not supported for rotated rasters')
		}
		rownr <- 1 + (trunc((ymax(object) - y) / yres(object)))
		rownr[y == ymin(object) ] <- object@nrows 
		rownr[y > ymax(object) | y < ymin(object)] <- NA
		return(as.vector(rownr))
	}	
)	


setMethod("xyFromCell", signature(object="BasicRaster", cell="ANY"), 
	function(object, cell, spatial=FALSE, ...) {
		if (rotated(object)) {
			xy <- object@rotation@transfun( 
				cbind(x=colFromCell(object, cell), y=rowFromCell(object, cell)) 
			)
		} else {
			e <- object@extent 
			xy <- .doXYFromCell(
				object@ncols, object@nrows,
				e@xmin, e@xmax, e@ymin, e@ymax, cell
			)
			dimnames(xy) <- list(NULL, c("x", "y"))
		}

		if (spatial) {
			xy <- SpatialPoints(stats::na.omit(xy), crs(object))
		}
		return(xy)
	}
)
	
	
if (!isGeneric("coordinates")) {
	setGeneric("coordinates", function(obj, ...)
		standardGeneric("coordinates"))
}	

		   
setMethod("coordinates", signature(obj="Raster"), 
    function(obj, ...){
		xyFromCell(obj, cell=1:ncell(obj), ...)
	}
)

setMethod("coordinates", signature(obj="Extent"), 
    function(obj, ...){
		e <- as.vector(obj)
		rbind(cbind(e[1], e[3:4]), cbind(e[2], e[4:3]))
	}
)


setMethod("yFromCell", signature(object="Raster",cell="numeric"), 
	function(object, cell) {
		if (rotated(object)) {
			xy <- xyFromCell(object, cell)
			return(xy[,2])
		} else {
			rows <- rowFromCell(object, cell)
			return( .yFromRow(object, rows) )
		}
	}  
)

	
setMethod("xFromCell", signature(object="Raster",cell="numeric"), 
	function(object, cell) {
		if (rotated(object)) {
			xy <- xyFromCell(object, cell)
			return(xy[,1])
		} else {
			cols <- colFromCell(object, cell)
			return( .xFromCol(object, cols) )
		}
	}  
)