creating multi-index from dataframe

Question

    Geography      Age group     2016
0  Toronto          All          1525
1  Toronto           1~7          5
2  Toronto           7~20          7
3  Toronto           20~40        500
4  Vancouver       All           3000
5  Vancouver       1~7            10
6  Vancouver       7~20          565
7  Vancouver       20~40         564
.
.
.

NOTE: This is just an example. my dataframe contains different numbers

I want to create multi-index where first index is by Geography and second is by age group.

Also is it possible to groupby w/o performing any functions at the end?

Output should be:

   Geography   Age group   2016
0  Toronto       All       1525
1                1~7         5
2                7~20        7
3                20~40      500
4  Vancouver     All       3000
5                1~7         10
6                7~20       565
7                20~40      564
.
.

yatu · Accepted Answer · 2019-03-07 15:58:27Z

4

In order to create a MultiIndex as specified, you can simply use DataFrame.set_index():

df.set_index(['Geography','Agegroup' ])

                    2016
Geography Age group      
Toronto   All       1525
          1~7          5
          7~20         7
          20~40      500
Vancouver All       3000
          1~7         10
          7~20       565
          20~40      564

answered Mar 7, 2019 at 15:58

yatu

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3 Comments

haneulkim Over a year ago

Perfect! Thank you.

haneulkim Over a year ago

But is it possible to do that using groupby?

yatu Over a year ago

If what you want is to create a MultiIndex dataframe, this is the correct way. Groupbys are intended to apply some aggregation function over the groups

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