Changed features.

        {threshdoc}

def unchanged(self, thresh=0.05, idx=True):
        """
        Changed features.

        {threshdoc}
        """
        ind = (
            (self.data[self.pval_column] > thresh)
            | np.isnan(self.data[self.pval_column])
        )
        if idx:
            return ind
        return self[ind]