Site descriptors for a subset of atoms

[siasolt]

Is it possible to compute ACE descriptors for a subset of atoms instead of all atoms in a simulation box?

site_descriptors(basis, atoms) extracts the feature vector for all atoms.

[cortner]

There is this:

site_descriptor(basis, atoms::AbstractAtoms, i::Integer)

which returns a single one. Since site_descriptors just broadcasts this one, I think you could just do one of the following:

[ site_descriptor(basis, atoms, i) for i in list] 
site_descriptor.(Ref(basis), Ref(atoms), list)

But it would be nice to have syntax for this, basically,

site_descriptors(basis, atoms, list) 

or something similar. Do you feel like making a PR?

[cortner]

actually it should be a very quick fix. I'll do this and let you know when it's done.