Pick the Best Output with dspy.BestOfN

Guide the user through using DSPy's BestOfN module to run a program multiple times and keep the highest-scoring result. This is rejection sampling -- generate N candidates, score each one, return the winner.

What is BestOfN

dspy.BestOfN wraps any DSPy module and calls it up to N times with temperature=1.0 (each attempt uses a different rollout ID to get diverse outputs). A reward function scores every result, and BestOfN returns the single best prediction.

If any attempt hits a score threshold you set, execution stops early -- no need to burn through all N attempts when you already have a great result.

Your module ──> Run N times ──> Score each with reward_fn ──> Return best

When to use BestOfN