Merged PR 546: Log the random seed used on each run

## Summary
Added changes so that the value of the random number seed is recorded in a log file when it's specified or the user asks for a RNG seed to be automatically generated.

## Test process
Updated existing RNG tests; added new test.

## Checklist
- [X] PR is linked to a **work item**
- [X] **acceptance criteria** of linked ticket are met
- [X] performed **self-review** of the code
- [X] written **tests** for any new functionality added with this PR
- [ ] updated the **documentation** if this PR changes or adds functionality
- [ ] written/updated **design docs** if this PR implements new functionality
- [X] updated the **change log**
- [X] ran **pre-commit** checks for code style
- [ ] attended to any **TO-DOs** left in the code

Related work items: #2879

src/primaite/game/game.py

@@ -80,6 +80,8 @@ class PrimaiteGameOptions(BaseModel):
 
     seed: int = None
     """Random number seed for RNGs."""
+    generate_seed_value: bool = False
+    """Internally generated seed value."""
     max_episode_length: int = 256
     """Maximum number of episodes for the PrimAITE game."""
     ports: List[str]

src/primaite/session/environment.py

@@ -26,14 +26,26 @@ except ModuleNotFoundError:
     _LOGGER.debug("Torch not available for importing")
 
 
-def set_random_seed(seed: int) -> Union[None, int]:
+def set_random_seed(seed: int, generate_seed_value: bool) -> Union[None, int]:
     """
     Set random number generators.
 
+    If seed is None or -1 and generate_seed_value is True randomly generate a
+    seed value.
+    If seed is > -1 and generate_seed_value is True ignore the latter and use
+    the provide seed value.
+
     :param seed: int
+    :param generate_seed_value: bool
+    :return: None or the int representing the seed used.
     """
     if seed is None or seed == -1:
-        return None
+        if generate_seed_value:
+            rng = np.random.default_rng()
+            # 2**32-1 is highest value for python RNG seed.
+            seed = int(rng.integers(low=0, high=2**32 - 1))
+        else:
+            return None
     elif seed < -1:
         raise ValueError("Invalid random number seed")
     # Seed python RNG
@@ -50,6 +62,13 @@ def set_random_seed(seed: int) -> Union[None, int]:
     return seed
 
 
+def log_seed_value(seed: int):
+    """Log the selected seed value to file."""
+    path = SIM_OUTPUT.path / "seed.log"
+    with open(path, "w") as file:
+        file.write(f"Seed value = {seed}")
+
+
 class PrimaiteGymEnv(gymnasium.Env):
     """
     Thin wrapper env to provide agents with a gymnasium API.
@@ -65,7 +84,8 @@ class PrimaiteGymEnv(gymnasium.Env):
         """Object that returns a config corresponding to the current episode."""
         self.seed = self.episode_scheduler(0).get("game", {}).get("seed")
         """Get RNG seed from config file. NB: Must be before game instantiation."""
-        self.seed = set_random_seed(self.seed)
+        self.generate_seed_value = self.episode_scheduler(0).get("game", {}).get("generate_seed_value")
+        self.seed = set_random_seed(self.seed, self.generate_seed_value)
         self.io = PrimaiteIO.from_config(self.episode_scheduler(0).get("io_settings", {}))
         """Handles IO for the environment. This produces sys logs, agent logs, etc."""
         self.game: PrimaiteGame = PrimaiteGame.from_config(self.episode_scheduler(0))
@@ -79,6 +99,8 @@ class PrimaiteGymEnv(gymnasium.Env):
 
         _LOGGER.info(f"PrimaiteGymEnv RNG seed = {self.seed}")
 
+        log_seed_value(self.seed)
+
     def action_masks(self) -> np.ndarray:
         """
         Return the action mask for the agent.
@@ -146,7 +168,7 @@ class PrimaiteGymEnv(gymnasium.Env):
             f"avg. reward: {self.agent.reward_function.total_reward}"
         )
         if seed is not None:
-            set_random_seed(seed)
+            set_random_seed(seed, self.generate_seed_value)
         self.total_reward_per_episode[self.episode_counter] = self.agent.reward_function.total_reward
 
         if self.io.settings.save_agent_actions: