Coin Selection about lucid HOT 6 OPEN

You can run a one-pass filter on the utxos to split off those that have the assets you are looking for, those that contain only Ada, and those that contain Ada and assets your are not looking for.

I also distinguish between utxos that have only the asset I am looking for.

Within those filtered results, you can run your Random Sampling in this order:

Asset(s)

1. Random sample through utxos with only the required asset as needed
2. Random sample through utxos with the required assed and other assets as needed

Ada

1. Random sample (or even largest-first) through the utxos with only ada as needed
2. Random sample through all utxos that have not been chosen yet

No improvement step because you are guaranteed to be done as every pick is an improvement...

Important Note: Do not forget to increase the target quantity of Ada within the utxos selection loop to account for the carry necessary to send back the change output. The change output might contain a large number of random assets and the Ada necessary to send it back in change is NOT Ada that can be counted towards your coin selection target.

from lucid.

More opinonated take : At the last step where you need to scrounge for Ada within a bunch of utxos with assets you do not need, I actually do a weighted sorting where the weight is

weight = Ada / (1 + Number of Assets ^ 2)

and pick from those in order from the largest to the smallest so as to minimize my grabbing random junk. But I admit this is might be a matter of (even more) debate.

from lucid.

Did you look at the implementation of the off-chain code handling that IOG provides in the Constraints module? Or do you see the above problems with that implementation as well?

from lucid.

The Contraints module helps you to build the tx in the way you need it. Lucid allows you to do exactly the same. So yeah this is covered as well. Basically any kind of transaction should be possible regardless of what you add and the coin selection should be able to find the right inputs.

from lucid.

Was this ever implemented? I would love to have a utils function in Lucid to do random improve coin selection for me, right now it looks like Nami is not really doing it by default with .getUTxOs

from lucid.

I wonder if this proposal could work with Lucid: cardano-foundation/CIPs#785

There is a sample implementation in CardanoSharp (C# library)

Implementation Code Example

An implementation example for all 3 core functions involved in the Optimized Random Improve selection can be found in this fork of the CardanoSharp Library here:

Aggregator Function - https://github.com/Orion-Crypto/cardanosharp-wallet/blob/optimized-coin-selection-example/CardanoSharp.Wallet/CIPs/CIP2/CoinSelectionService.cs
Select Inputs Function - https://github.com/Orion-Crypto/cardanosharp-wallet/blob/optimized-coin-selection-example/CardanoSharp.Wallet/CIPs/CIP2/CoinSelectionStrategies/OptimizedRandomImproveStrategy.cs
Change Selection Function - https://github.com/Orion-Crypto/cardanosharp-wallet/blob/optimized-coin-selection-example/CardanoSharp.Wallet/CIPs/CIP2/ChangeCreationStrategies/MultiSplitChangeSelectionStrategy.cs

from lucid.