'create a (n_levels, n_levels) array with corrected p_values
this needs to improve, similar to R pairwise output'

def pval_table(self):

    k = self.n_levels
    pvals_mat = np.zeros((k, k))
    pvals_mat[lzip(*self.all_pairs)] = self.pval_corrected()
    return pvals_mat
