>From the R code snippet I see: "Surprisingly, the value 9.75 is shifted to
>106, 86 = 105,85 in Python indexing", but R is 1-base and Python 0-base. In R:
> library(terra)
terra 1.7.71
> gdal()
[1] "3.8.3"
> a <- rast("attachment.obj")
> b <- rast("st4_pr.2017092016.01h.tif")
> a
class : SpatRaster
dimensions : 205, 205, 1 (nrow, ncol, nlyr)
resolution : 4762, 4762 (x, y)
extent : 4940902, 5917112, -7210793, -6234583 (xmin, xmax, ymin, ymax)
coord. ref. : +proj=stere +lat_0=90 +lat_ts=60 +lon_0=-105 +x_0=0 +y_0=0
+R=6367470 +units=m +no_defs
source : attachment.obj
name : SFC (Ground or water surface); Total precipitation [kg/m^2]
unit : kg/m^2
time : 2017-09-20 16:00:00 UTC
> b
class : SpatRaster
dimensions : 205, 205, 1 (nrow, ncol, nlyr)
resolution : 4762, 4762 (x, y)
extent : 4940902, 5917112, -7210793, -6234583 (xmin, xmax, ymin, ymax)
coord. ref. : +proj=stere +lat_0=90 +lat_ts=60 +lon_0=-105 +x_0=0 +y_0=0
+R=6367470 +units=m +no_defs
source : st4_pr.2017092016.01h.tif
name : 0[-] SFC (Ground or water surface)
> all.equal(values(a), values(b))
[1] "Attributes: < Component \"dimnames\": Component 2: 1 string mismatch >"
> dimnames(values(a))
[[1]]
NULL
[[2]]
[1] "SFC (Ground or water surface); Total precipitation [kg/m^2]"
> dimnames(values(b))
[[1]]
NULL
[[2]]
[1] "0[-] SFC (Ground or water surface)"
> all.equal(values(a), values(b), check.attributes=FALSE)
[1] TRUE
Reading both into R shows that the input GRIB data and the GTiff data converted
by gdal_translate are identical.
By the way, better to use the terra package directly, raster uses it indirectly.
Hope this clarifies,
Roger
--
Roger Bivand
Emeritus Professor
Norwegian School of Economics
Postboks 3490 Ytre Sandviken, 5045 Bergen, Norway
roger.biv...@nhh.no
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