def select_variant()

in lambda/api/algorithm.py [0:0]

• 8 lines of code
• 2 McCabe index (conditional complexity)

    def select_variant(self):
        """
        Tompson sampling uses Beta distribution takes two parameters, ‘α’ (alpha) and ‘β’ (beta).
        In the simplest terms these parameters can be thought of as respectively the count of successes and failures.
        see: https://towardsdatascience.com/thompson-sampling-fc28817eacb8
        """
        probs = []
        for v in self.variant_metrics:
            success = v["reward_sum"]
            failure = v["invocation_count"] - success
            probs.append(AlgorithmBase.random_beta(1 + success, 1 + failure))
        variant_index = AlgorithmBase.argmax(probs)
        return self.variant_metrics[variant_index]["variant_name"]