Merge pull request #170 from inbo/rgdal

Drop rgdal-related messages

R/n2khab.R

@@ -14,19 +14,6 @@ utils::globalVariables(c("."))
 .onAttach <- function(libname, pkgname) {
   packageStartupMessage(
     "Attaching n2khab version ",
-    packageVersion("n2khab"), ".\n"
-  )
-  packageStartupMessage(
-    "When working with raster objects returned by n2khab, you can safely\n",
-    "mute proj4string degradation warnings:",
-    "\n\noptions(rgdal_show_exportToProj4_warnings = \"none\")\n\n",
-    "You must do this before using the n2khab functions ",
-    "depending on \nrgdal or raster, and before loading ",
-    "the latter (or sp).\n\n",
-    "Do note that those warnings are applicable: in the returned raster\n",
-    "objects, the proj4string is effectively degraded and should not ",
-    "be used.\n",
-    "See https://inbo.github.io/n2khab/#suppressing-rgdal-warnings-about-",
-    "proj4string-degradation\nfor more information."
+    packageVersion("n2khab")
   )
 }

README.md

@@ -57,24 +57,14 @@ There is a major distinction between:
 - **raw data** ([Zenodo-link](https://zenodo.org/communities/n2khab-data-raw)), to be stored in a folder `n2khab_data/10_raw`;
 - **processed data** ([Zenodo-link](https://zenodo.org/communities/n2khab-data-processed)), to be stored in a folder `n2khab_data/20_processed`.
 
-### Suppressing `rgdal` warnings about proj4string degradation
+### Note: don't use proj4strings to define coordinate reference systems
 
-Setting coordinate reference systems (CRS) of geospatial R objects is taken care of by the package, in a way that is compatible with older and current versions of PROJ and GDAL backend libraries.
-This is done by gratefully implementing such features from the `sf` and `sp` packages.
-The functions never specify a CRS by means of a proj4string, which is an aged format not supported by the current backend versions.
+If you use `RasterLayer` or `RasterBrick` objects returned by **n2khab** functions, please make sure to not use the proj4string to represent its coordinate reference system (CRS), even while printing those objects will show a degraded (!) proj4string.
+The proj4string is an aged format which has lost most of its ability to represent a geodetic datum.
 
-Please note that nonetheless you will see warnings about degraded proj4strings when using certain `n2khab` functions or when converting resulting `sf` objects to `sp` objects.
-This is normal!
-It is the current default behaviour of `rgdal` to yield these warnings.
-However in the case of `n2khab` functions and resulting objects these warnings are trivial and unnecessary.
-You can suppress them in your R scripts by inserting below statement _before_ loading geospatial packages:
-
-```r
-options(rgdal_show_exportToProj4_warnings = "none")
-```
+The proper CRS representation is the WKT string, which is effectively returned by `raster::wkt()` and by `raster::crs()`.
 
 See [this](https://inbo.github.io/tutorials/tutorials/spatial_crs_coding/) tutorial if you would like to learn more about this.
-In short: _don't_ use proj4strings to define CRSs!
 
 ## You are welcome to contribute!