Iterating through variants

[hyanwong]

Possibly more of a zarr question, but I want to iterate over the variant information in an SGkit file, when that information is scattered over a number of arrays.

For example in my case, I want to look at the ancestral allele defined in variant_AA, do some string manipulation (e.g. change it to uppercase / lowercase), match the result against the corresponding list in variant.alleles, and then save it in a new array.

In other works, it would be useful to jointly iterate over arrays using e.g. zip. Something like

for aa, alleles in zip(ds.variant_AA, ds.alleles):  # probably doesn't work
    anc = aa.split("|")[0].lower()
    if anc in alleles:
        # do something
    # Save `anc` back out to another Zarr array - not sure how?

I imagine this sort of joint iteration is generally useful, but being a SGkit newbie, have no idea what the recommended approach is. Could it be added to the FAQ?