moref的博客

multi_tuple = MultiIndex.from_tuples(tuples=col_tuples) # 将元组转变成多层索引。df = pd.merge(df1，df2，how = ‘left’， on = ['a', 'b']) #运行成功。df2.columns = df2.columns.droplevel(0) #去掉第一层索引。报错原因：索引层级不匹配，如左表为单层（行列）索引，但右表为多层（行列）索引。col_tuples = {('第一层索引’, '第二层索引')}