Allow some non-leaf taxa to be added to the CV model

[upupa-epops]

@victorengel

A possible simple workaround is to change the algorithm not to learn the species until there are some threshold number of species eligible for training. Right now that threshold is 1. It should be a higher number. I would suggest 2 to start.

@upupa-epops

I think there are probably ways that the CV could be optimized to reduce this, but I feel like it would be pretty complicated and take a bunch of problem-solving to figure out how to do it well.

The main question I think is how do you make it aware that other similar species exist, if there aren’t enough observations of them for those species to be added to the training pool? If it isn’t aware of the species then it doesn’t know whether they look identical to the species it knows vs. existing but being very distinct, or even whether they exist at all.

@upupa-epops

If there is another species in the mushroom genus with 0 observations anywhere in the world, should that kill the CV’s confidence for identifying any species in that genus?

An equivalent situation from the CV’s perspective might be a genus of birds that contains some highly identifiable species, plus a couple lost species with 0 observations that are probably extinct (e.g. Campephilus woodpeckers). I wouldn’t want to kill the CV’s ability to ID those distinctive extant species.

Ideally this problem could be automated but if it can be, it would be somewhat complicated and take some workshopping to figure out the right decisions to make, comparing ratios of species and observation numbers. This is especially the case with incomplete taxa where the full taxonomy isn’t loaded into iNat yet (e.g. there’s no way for the CV to tell if all species in a plant or insect genus are included on iNat yet). I’m not sure if there’s any way to automate it that wouldn’t just cause significant problems with obvious species IDs.