rasterFromXYZ generates an unexpected blank line

Question

I converted a raster to a dataframe by rasterToPoints, then converted it back to raster using rasterFromXYZ. An unexpected blank line appeared on the second raster as shown below. Any way to avoid this?

Answer 1

For example you can do (reproducible example)

library(raster)
f <- system.file("external/test.grd", package="raster")
r <- raster(f)
v <- as.matrix(r)
v <- v * 2
x <- setValues(r, v)

But in most cases it is not advisable to go this route as you can do almost any operation on the Raster objects themselves.

With your data I do:

r <- raster("bv2.tif")
x <- rasterToPoints(r)
z <- rasterFromXYZ(x)
e <- extent(-121.4,-114.6,49,50.4)
zoom(z, e)

And there is no white line. Zooming in further does not show an irregularity either. So this may be a problem with the tool you used to produce your maps.

This is confirmed by

sum(values(z) != values(r), na.rm=TRUE)
# [1] 0
cellStats(r, 'countNA')
# [1] 2130763
cellStats(z, 'countNA')
# [1] 2130763