Can not Save SARSA in Accord.NET
Accord.NET is a powerful framework for machine learning in C#. While it offers various reinforcement learning algorithms, saving a SARSA (State-Action-Reward-State-Action) agent directly is not currently supported.
Understanding the Issue
Accord.NET’s SARSA implementation is designed for real-time learning, where the agent updates its policy based on immediate experiences. This makes saving the entire agent’s state (including its policy) challenging for the following reasons:
- Dynamic Policy: The SARSA agent’s policy changes constantly during training. Saving the policy at a specific point might not accurately represent its future behavior.
- No Explicit Model: SARSA is a model-free algorithm, meaning it does not explicitly learn a model of the environment. This makes it difficult to store the agent’s knowledge in a way that can be easily restored.
Workarounds
While saving the SARSA agent itself is not directly supported, you can adopt workarounds to preserve and restore its learned knowledge:
1. Saving the Q-Table
The core of the SARSA agent’s learning process is the Q-table, which represents the expected future rewards for each state-action pair. You can save this table to a file:
Action | State 1 | State 2 |
---|---|---|
Action 1 | Q(State 1, Action 1) | Q(State 2, Action 1) |
Action 2 | Q(State 1, Action 2) | Q(State 2, Action 2) |
using Accord.MachineLearning.Reinforcement.Learning; // ... Code to train the SARSA agent // Access the Q-table: double[,] qTable = sarsaAgent.QTable; // Save the Q-table to a file (e.g., using CSV or a binary format) // ...
To restore the agent, you can load the saved Q-table and create a new SARSA agent with these values.
2. Serializing the Agent’s Internal Parameters
You can attempt to serialize the SARSA agent’s internal parameters using a serialization library (like BinaryFormatter or Json.NET). However, this is not officially supported and may require careful adjustments based on the specific implementation details.
// ... Code to train the SARSA agent // Serialize the agent's parameters: using (var stream = new FileStream("sarsa_agent.dat", FileMode.Create)) { var formatter = new BinaryFormatter(); formatter.Serialize(stream, sarsaAgent); } // ... Code to deserialize and load the agent: using (var stream = new FileStream("sarsa_agent.dat", FileMode.Open)) { var formatter = new BinaryFormatter(); sarsaAgent = (SARSA)formatter.Deserialize(stream); }
Conclusion
Saving a SARSA agent directly in Accord.NET is not supported. However, you can use workarounds such as saving the Q-table or attempting to serialize internal parameters. Remember to carefully consider the trade-offs and ensure that your chosen method aligns with your specific application requirements.