include groupby column values in result-CodePudding

I use groupby by "department" and then apply a function to the column "flight_length" The desired result look something like this

However, only the co2_footprint column was returned (the value column). I want to include the department column as well. How do I do that?

Here is the code that I used:

def co2_footprint(value):
    return value * 0.1

print(df.groupby('department')['flight_length'].apply(co2_footprint))

what the data look like:

CodePudding user response：

Your function is not correct, missing an aggregate function like sum, mean or whatever aggregation custom function:

Try:

def co2_footprint(value):
    return sum(value * 0.1)

>>> df.groupby('department')['flight_length'].apply(co2_footprint).reset_index()

  department  flight_length
0  Marketing     159.914594

CodePudding user response：

Try this df.groupby('department')['flight_length'].apply(co2_footprint).reset_index()

If it does not work, better way is to use pd.pivot_table() function. Read more here: