Copy resolution extent CRS metadata from one raster file to another using raster R

Question

I have two geotiff raster files, one has all the metadata information and in the other the information was lost. I know that all the metadata information was exactly the same so I want to copy it from one file to the other. I tried to use raster, because I made all the processing in R.

This is the file with metadata

af1_patch <-raster(a_files[6])

af1_patch

class       : RasterLayer 
dimensions  : 38400, 38400, 1474560000  (nrow, ncol, ncell)
resolution  : 231.656, 231.656  (x, y)
extent      : -2223901, 6671703, -4447802, 4447802  (xmin, xmax, ymin, ymax)
coord. ref. : +proj=sinu +lon_0=0 +x_0=0 +y_0=0 +a=6371007.181 +b=6371007.181 +units=m +no_defs 
data source : Forest_patches_AF_1.tif 
names       : Forest_patches_AF_1 
values      : 0, 255  (min, max)

And this is the file without the metadata

af1_area <-raster(a_files[1])

af1_area

class       : RasterLayer 
dimensions  : 38400, 38400, 1474560000  (nrow, ncol, ncell)
resolution  : 1, 1  (x, y)
extent      : 0, 38400, 0, 38400  (xmin, xmax, ymin, ymax)
coord. ref. : NA 
data source : africa_AF_1.tif 
names       : africa_AF_1 
values      : 0, 255  (min, max)

I tried to copy the metadata using:

res(af1_area) <- res(af1_patch)
crs(af1_area) <- crs(af1_patch)
extent(af1_area) <- extent(af1_patch)

but it doesn't work, dimensions and resolution are incorrect and the data values are lost:

af1_area

class       : RasterLayer 
dimensions  : 166, 166, 27556  (nrow, ncol, ncell)
resolution  : 53588, 53588  (x, y)
extent      : -2223901, 6671703, -4447802, 4447802  (xmin, xmax, ymin, ymax)
coord. ref. : +proj=sinu +lon_0=0 +x_0=0 +y_0=0 +a=6371007.181 +b=6371007.181 +units=m +no_defs 


 hist(af1_area)

   Error in .hist1(x, maxpixels = maxpixels, main = main, plot = plot, ...) : 
   cannot make a histogram; need data on disk or in memory

Answer 1

You were very close. You just need to set the extent and the CRS; but you should not explicitly change the resolution -- as that action will discard the cell values. The resolution is changed implicitly by changing the extent. So all you need to do is:

crs(af1_area) <- crs(af1_patch)
extent(af1_area) <- extent(af1_patch)

Answer 2

I can't reproduce your error, the approach described works for me (the res() values are changed to what I assigned), but note that the "value" field in your last output is gone (same with mine) so that's probably not the way to go.

I use GDAL for a similar process (gdalcopyproj.py)

gdalcopyproj.py source_file dest_file

If you want to stick with R use:

library(raster)
?resample()