多索引不会在python中将相同的键分组

Question

这是我的数据框，我希望使用列["State", "RegionName"]

设置多索引

    RegionName    State Metro            CountyName      SizeRank
1   Los Angeles   CA    Los Angeles-Long Beach-Anaheim   2
2   Chicago       IL    Chicago          Cook            3
3   Philadelphia  PA    Philadelphia     Philadelphia    4
4   Phoenix       AZ    Phoenix          Maricopa        5
5   Las Vegas     NV    Las Vegas        Clark           6
6   San Diego     CA    San Diego        San Diego       7
7   Dallas        TX    Dallas-Fort      Worth  Dallas   8
8   San Jose      CA    San Jose         Santa Clara     9
9   Jacksonville  FL    Jacksonville     Duval           10

我的代码：

multi_gdp_df = gdp_df.set_index([gdp_df['State'], gdp_df['RegionName']], drop=False)

然后我得到的结果是，该地区属于同一州“ CA”没有分组

                        Metro                           CountyName    SizeRank
State   RegionName          
CA      Los Angeles     Los Angeles-Long Beach-Anaheim  Los Angeles   2
IL      Chicago         Chicago                         Cook          3
PA      Philadelphia    Philadelphia                    Philadelphia  4
AZ      Phoenix         Phoenix                         Maricopa      5
NV      Las Vegas       Las Vegas                       Clark         6
CA      San Diego       San Diego                       San Diego     7
TX      Dallas          Dallas-Fort Worth               Dallas        8
CA      San Jose        San Jose                        Santa Clara   9
FL      Jacksonville    Jacksonville                    Duval         10

如何使具有区域组的数据框处于相同状态？