Umberto Lupo

Note: In discussion with @wreise, we noted that in the case of extended persistence one cannot dispose of all zero-persistence pairs. Zero-persistence pairs created in "different sweeps" are essential bars...

@wreise thanks for the thorough look! Of course there are still docs to write but more importantly we can't really ship this without intervening in some way on the downstream...

Another point is that the input validation is inadequate still (my fault) because really this transformer should only work with sparse input, and yet we don't throw a useful error...

Thanks! Yes, we noticed that before but it slipped due to other priorities, good it's now here so we don't forget!

@gtauzin I had never seen this before! It reminds me of the fact that I once thought it would be a good idea to have a sorting transformer to sort...

@gtauzin I'm thinking that this transformer can also be seen as a "representation" and not as a "feature generator". Of course the boundary has always been blurry, but I was...

> If I was to define what a representation is, I would say that it is an object whose visualization is useful to understand the information contained in a persistence...

> We should allow here n_distances to be a list as for ComplexPolynomial #479. This is now possible following #502. I'll make the change.

@gtauzin thanks for the patience and for the suggestions. I'm happy with the practical criterion you mentioned, that anything outputting 2D arrays is a feature generator. So let's keep both...

@Amg88, so as to keep this on record, could you please provide here the specifications for this function?