Output Newick without branch lengths

[hyanwong]

A trivial thing, but it would be useful for me to output a Newick tree (or indeed a set of nexus trees) without branch lengths. I wonder if that's a useful thing to do if precision=None? Or if that's a bit too cryptic, and overriding the normal use of None as a marker for the default value of a parameter?

[jeromekelleher]

I'd slightly worry about using None in a way that's not "use the default value" here. What about having a negative precision meaning "don't print out branch lengths"? It sort of makes sense.

The only other option is to add another parameter branch_lengths=True. This is perhaps a bit more extensible, since we might want to add other stuff into the newick in the future (like, say, metadata encoded as extended newick) and precision might apply across a number of different things, not just branch lengths.

Either way, I wouldn't bother implementing in the C engine.

[hyanwong]

I'd slightly worry about using None in a way that's not "use the default value" here.

Yes, I thought that too.

What about having a negative precision meaning "don't print out branch lengths"? It sort of makes sense.

I guess there's no other meaning. We could make it a bit more intuitive to the reader by recommending the use of tskit.NULL

The only other option is to add another parameter branch_lengths=True. This is perhaps a bit more extensible, since we might want to add other stuff into the newick in the future (like, say, metadata encoded as extended newick) and precision might apply across a number of different things, not just branch lengths.

Whatever you think best.

Either way, I wouldn't bother implementing in the C engine.

Agreed.

[jeromekelleher]

Probably simplest to add a new parameter, branch_lenghths=True. It's the least cryptic and most discoverable.

[hyanwong]

Fixed in #931