Create a Raster* object from x, y, z values
Create a Raster* object from x, y and z values. x and y represent spatial coordinates and must be on a regular grid. If the resolution is not supplied, it is assumed to be the minimum distance between x and y coordinates, but a resolution of up to 10 times smaller is evaluated if a regular grid can otherwise not be created. z values can be single or multiple columns (variables) If the exact properties of the RasterLayer are known beforehand, it may be preferable to simply create a new RasterLayer with the raster function instead, compute cell numbers and assign the values with these (see example below).
rasterFromXYZ(xyz, res=c(NA,NA), crs="", digits=5)
xyz |
matrix or data.frame with at least three columns: x and y coordinates, and values (z). There may be several 'z' variables (columns) |
res |
numeric. The x and y cell resolution (optional) |
crs |
CRS object or a character string describing a projection and datum in PROJ.4 format |
digits |
numeric, indicating the requested precision for detecting whether points are on a regular grid (a low number of digits is a low precision) |
RasterLayer or RasterBrick
See rasterize for points that are not on a regular grid
r <- raster(nrow=5, ncol=5, xmn=0, xmx=10, ymn=0, ymx=10, crs="") set.seed(1) values(r) <- sample(1:25) r[r < 15] <- NA xyz <- rasterToPoints(r) rst <- rasterFromXYZ(xyz) # equivalent to: rr <- raster(nrow=5, ncol=5, xmn=0, xmx=10, ymn=0, ymx=10) cells <- cellFromXY(rr, xyz[,1:2]) rr[cells] <- xyz[,3] # multiple layers xyzz <- cbind(xyz, a=1:nrow(xyz), b=nrow(xyz):1) b <- rasterFromXYZ(xyzz)
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