def compute_metric(self, components):
        """Compute recall from `components`"""
        numerator = components[RECALL_RELEVANT_RETRIEVED]
        denominator = components[RECALL_RELEVANT]
        if denominator == 0.:
            if numerator == 0:
                return 1.
            else:
                raise ValueError('')
        else:
            return numerator/denominator
Compute recall from `components`