CODEWITHSUNDEEP
pythonjoinpandasgroup-by
Denis Denis
Denis Denis

Reputation: 1

Python 2.7 groupby and then join

My question is about how to join 2 dataframes, which were created by the groupby method and the sum() and max() functions.

The case is: I have 1st dataframe with next structure:

enter image description here

And the second one with the same structure, but instead of DepartmentDescripton... variables, I have "Monday", "Tuesday" etc.

Then I try to join them:

train_joined_dep_week = pd.merge(tr_bin_dep_grouped, tr_bin_weekday_grouped_flag, left_on=["VisitNumber"], right_on=["VisitNumber"], how='INNER')`

the error is 

KeyError
Traceback (most recent call last)
<ipython-input-24-faccedccea7d> in <module>()
----> 1 train_joined_dep_week = pd.merge(tr_bin_dep_grouped, tr_bin_weekday_grouped_flag, left_on=["VisitNumber"], right_on=["VisitNumber"], how='INNER')
[...]
KeyError: 'VisitNumber'

Note: I have two different functions for aggregation (sum() and max()), so I can't just make 1 dataframe. I believe the problem is about wrong data structure after sum() func, but I don't understand how to make it in right way.

Upvotes: 0

Views: 205

Answers (1)

mattvivier
mattvivier

Reputation: 2291

When you aggregate using groupby the columns you're grouping by get moved into the index. You should be able to reset the index with tr_bin_dep_grouped.reset_index(inplace=True) and then merge the two dataframes together.

Upvotes: 1

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