Pandas select index from grouped dataframe

Question

I have the foll dataframe (grp):

key  ColA   ColB
2    23.4   33.4
3    43.2   45.3
4    12.3   90.3
5    11.2   77.3

grp is the result of a groupby operation performed earlier. Here 'key' is the index.

How can I create another dataframe with 'key' and 'ColA' as its elements? Right now, I cannot seem to select 'key'

Is grp really a dataframe, or is it just a groupby object? Also, is key a column, or is it the index? — BrenBarn
– BrenBarn, Commented May 15, 2014 at 2:58

YS-L · Accepted Answer · 2014-05-15 03:00:27Z

1

You can use reset_index. Assuming grp is the DataFrame as you have described:

res = grp['ColA'].reset_index()
# res is now a DataFrame with key and ColA as the columns

answered May 15, 2014 at 3:00

YS-L

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2 Comments

thanks, does this extend if I want to select ColB as well? What will the syntax look like then?

You can either use grp[['ColA', 'ColB']].reset_index(), or simply grp.reset_index() if there are only two columns in total.