R 中两个栅格的匹配范围

Question

I have two raster:

  raster1
  
  class       : SpatRaster 
  dimensions  : 21600, 43200, 1  (nrow, ncol, nlyr)
  resolution  : 0.008333333, 0.008333333  (x, y)
  extent      : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)

  raster2
  
  class       : SpatRaster 
  dimensions  : 720, 1440, 1  (nrow, ncol, nlyr)
  resolution  : 0.25, 0.25  (x, y)
  extent      : -180, 180, -90, 90  (xmin, xmax, ymin, ymax)
  coord. ref. : lon/lat WGS 84 

I want to run zonal stastics to calculate sum of smaller raster raster1 on bigger raster raster2 :

  terra::zonal(raster1, raster2, fun = sum, as.raster=T, filename = 'zonal.tif') 
  Error: [zonal] dimensions and/or extent do not match
  

I wasn't sure why the extent are not matching until I did this

  terra::ext(raster1)
  SpatExtent : -180.000001017276, 180.000001017276, -90.0000010172997, 90.0000010172997 (xmin, xmax, ymin, ymax)
  
  terra::ext(raster2)
  SpatExtent : -180, 180, -90, 90 (xmin, xmax, ymin, ymax)
  

which shows that raster1 extent have some imprecision. What are different ways I can fix this?

EDIT: I tried the suggestion in the comment

terra::crs(raster2) <- sf::st_crs(4326)$wkt
terra::crs(raster1) <- sf::st_crs(4326)$wkt

terra::ext(raster2)
SpatExtent : -180, 180, -90, 90 (xmin, xmax, ymin, ymax)

terra::ext(raster1)
SpatExtent : -180.000001017276, 180.000001017276, -90.0000010172997, 90.0000010172997 (xmin, xmax, ymin, ymax)
  

But my extent are still not matching

Answer 1

The error message is

Error: [zonal] dimensions and/or extent do not match

In this case, that clearly refers to the difference is dimensions, which are

#dimensions  : 21600, 43200, 1  (nrow, ncol, nlyr)
#dimensions  : 720, 1440, 1  (nrow, ncol, nlyr)

I do not think the small difference in the extent is relevant at all.

To make the dimensions match you can use disagg or aggregate with a factor of 30.

If the crs of raster2 is different from that of raster1 you can (in this case, where you clearly have two global lon/lat rasters) fix that with

crs(raster2) <- crs(raster1)

And for good measure, you could in this case also do

ext(raster2) <- ext(raster1)

Answer 2

Mismatching extents don't stop zonal working, so I think that error message is wrong. Here's two rasters that only differ in their CRS:

> library(terra)
terra 1.5.21
> raster1 = rast()
> raster1[]=1:360
> raster2 = rast()
> raster2[]=1:360
> crs(raster1) = ""
> zonal(raster1, raster2)
Error: [zonal] dimensions and/or extent do not match

I guess it could be argued that a different CRS means a different extent in the same way that "23" is different to "23 km". But the extent and the dimensions are all the same according to these tests:

> ext(raster1) == ext(raster2)
[1] TRUE
> dim(raster1) == dim(raster2)
[1] TRUE TRUE TRUE

Rasters with a different extent work fine with zonal (once I've set the CRSs to match):

> ext(raster2) = c(-180.01, 180.01, -90.01, 90.01)
> crs(raster2) = ""
> z = zonal(raster1, raster2)
> 

If you do want to change an extent, you can use ext(r) =... as above, but you should try and figure out why extents don't match. Likely its because you have data on points and you may have cells extending out from points...