Virtual Guns with Swarm Targeting?

I thought that Diamond is also using virtual guns in melee (for he is using DisplacementVector in melee for his ASGun, while using GF in 1v1). But the code shows that the VGs is only used when there is only one opponent.

I've been long thinking about melee virtual guns, as nowadays, melee wave surfing is growing in popularity. However, the first difficulty to solve is to make VGs work with Targeting.

Here are the choices I've came up with:

• Keep track of VG ratings for each opponent, and aim with the best gun respectively. Then combine the results as if they were from the same gun, not very different guns. The problem is that swarm targeting may not work properly when internal data from two quite different guns is combined.
• Keep track of an overall rating, considering every opponent. However this method doesn't scale well when the opponents changes, e.g. going from 3 bots melee to 2 bots duel, the rating will remain irrelevant for a while.
• Keep track of VG ratings for each opponent, but aim with the same gun for every opponent (for better swarm targeting). The gun used to aim is chosen so that the overall hit-rate is maxed. This should be the most versatile approach, but not easy to implement.

Any thoughts here?

I think the best would be having individual guns, and using leave-one-out cross validation to test which gun actually gives better results on the historical data at fire time. This would skip needing to track separate hitrates for guns that you don't know where they would fire.

If I understand correctly, for n firing waves w = {w1..wn}, LOOCV involves training the gun with w - {wi}, then test with wi, for all i. For knn guns, this means doing n “(k+1)nn” searches (then exclude wi from result), and for neural networks, this means feeding the network n(n-1) waves in total. Isn’t that costly for robocode? Or may there be some faster ways?

Medina currently implements the third approach, but it only uses a HOT and a PIF gun, which implies in no improvement, but is meant to be a place to work on in the future. It uses different ratings depending on the number of enemies alive.