def read(fname):
    return open(os.path.join(os.path.dirname(__file__), fname)).read()
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)