How to write a tree with a jagged array as a branch?

Question

I would like to write a tree with two branches. One branch contains a single number per fill and the other branch contains a variable length array per fill. From the documentation, I can see how to do the first, but not how to do the second?

Answer 1

The answer is that this is a missing feature: https://github.com/scikit-hep/uproot/issues/354

As a "writing improvement," it probably has the highest benefit-over-effort ratio, but right now, we'd need a volunteer to get it done. Reik is assigned to that item, but he's both in school and gearing up for a different project. If you know anyone who wants to deal with byte manipulation and make a big impact, let me know!