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Fix: Auto-increment seed across batch_run iterations #2841

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Fix: Auto-increment seed across batch_run iterations #2841

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Fix: Auto-increment seed across batch_run iterations
EwoutH Oct 7, 2025
c03c6fa
[pre-commit.ci] auto fixes from pre-commit.com hooks
pre-commit-ci[bot] Oct 7, 2025
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8 changes: 8 additions & 0 deletions mesa/batchrunner.py
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Original file line number Diff line number Diff line change
Expand Up @@ -170,6 +170,14 @@ def _model_run_func(
Return model_data, agent_data from the reporters
"""
run_id, iteration, kwargs = run

# Handle seed uniqueness across iterations
if "seed" in kwargs and kwargs["seed"] is not None and iteration > 0:
seed_value = kwargs["seed"]
if isinstance(seed_value, (int, float)) and not isinstance(seed_value, bool):
kwargs = kwargs.copy()
kwargs["seed"] = int(seed_value) + iteration
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Suggested change
kwargs["seed"] = int(seed_value) + iteration
kwargs["seed"] = seed_value + time.time()

This is all that is needed to ensure a much better spread of seeding values and thus better randomness.


model = model_cls(**kwargs)
while model.running and model.steps <= max_steps:
model.step()
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