def __init__(self, assets_dir=None, requirements_file="requirements.yml"):
        self.assets_dir = assets_dir or Path(".") / "assets"
        self.requirements = GroupedRequirements()
        self.requirements.load(requirements_file)
        self.temp_dir = mkdtemp()
def heidke_skill_score(self):
        n = float(self.table.sum())
        nf = self.table.sum(axis=1)
        no = self.table.sum(axis=0)
        correct = float(self.table.trace())
        return (correct / n - (nf * no).sum() / n ** 2) / (1 - (nf * no).sum() / n ** 2)