Converting matrix to a WGS84 raster is rotated the wrong way

Question

I have a matrix like so:

xy <- matrix(rnorm(128 * 64),128,64)

and I want to turn it to a raster in WGS84.

I also have a longitude and a latitude matrix:

with the following dimensions:

min(lon) <- 0
max(lon  <- 357.1875
min(lat) <- -87.8638
max(lat) <- 87.8638

the latitude and longitude came for a netCDF, and for some reason the longitude is from 0 - 360 instead of -180 to 180, for now I am not worried about that though.

I try to create the raster like so:

r <- raster(xy, xmn = min(lon), xmx = max(lon), ymn = min(lat), ymx = max(lat), crs = CRS("+init=epsg:4326"))

but this returns:

Answer 1

Check out raster::rotate for your coordinate issues.

If that doesn't solve the orientation I sometimes need to use raster::flip. Occasionally I get text file grids that require this treatment.