Retired rgdal and maptools dependencies prevent installation on recent R versions

[kmkamilkhel]

Issue Description:

I am facing installation issues with the landmap package due to its dependencies on rgdal and maptools, which have been retired from CRAN as of October 2023. The installation fails because these packages are no longer available, and the functionality they provided has been replaced by newer packages like sf, terra, and stars.

Error Output:

arduino
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ERROR: dependencies 'rgdal', 'maptools' are not available for package 'landmap'
Suggested Solution: To ensure compatibility with modern R versions, I propose updating the package by replacing rgdal and maptools with the following modern alternatives:

Replace rgdal functions with sf (e.g., sf::st_read() instead of rgdal::readOGR()).
Replace maptools functionalities with terra for raster operations.
This update will maintain the functionality of the package while ensuring users can install it on recent R versions without issue.

Steps to Reproduce:

Run the following command in R 4.4.1 or later:
r
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devtools::install_github("envirometrix/landmap")
Installation fails due to missing dependencies rgdal and maptools.
Additional Comments: I am happy to help with testing and contribute to this transition if necessary.

Thank you for your work on this package!