Where should `sc.datasets` put data?

I’m adding that expression atlas downloader now (#489), and wondering where the files should go.

pbmc68k_reduced and toggleswitch put the datasets relative to where scanpy is installed (via __file__). All other functions place the data relative to where the python process was started.

While I like not storing the same files all over a filesystem, I’m not sure in the scanpy installation directory is the right place to be storing data.

Thoughts?

[flying-sheep]

The scanpy install directory is super wrong, as it’s not writable for many people.

There’s exactly one correct way of determining a global place for cache* files like this: appdirs.user_cache_dir(...)

Alex and me talked in the past and decided for a visible directory in the working directory. I’d be up for changing it to user_cache_dir(…) for the data.

*the data are cache files since reexccuting their function after deleting the files will redownload them without loss of information.

[flying-sheep]

All good, thank you for your work!