使用 Python 在数据框中添加平均值列

Question

I want to create a new data frame consisting of sex, amount of children, price of insurance, and if an individual is a smoker or not. Below is an example of my data frame.

Sex    Children Insurance Smoker
Male      3      392.48    Yes
Male      6      782.68    Yes
Male      6      438.21    No 
Female    1      125.98    Yes
Female    1      58.32     No
Female    4      585.12    Yes
Female    4      356.12    No

So far I got this using the code

df = pd.DataFrame(insurance).groupby(["sex", "children", "smoker"]).size()

#which outputs
sex      children   smoker
female   1          yes      1
         1          no       1
         4          yes      1
         4          no       1
male     3          yes      2
         6          yes      1
         6          no       1

How would I add a column of the average of insurance for each gender depending on how many children they have and if they smoke or not? I tried adding mean("insurance") but got an error, of course. Thank you so much for the help!

Answer 1

df.groupby(["Sex", "Children", "Smoker"],as_index=False)["Insurance"].mean()

#output

    Sex Children Smoker Insurance
0   Female  1     No    58.32
1   Female  1     Yes   125.98
2   Female  4     No    356.12
3   Female  4     Yes   585.12
4   Male    3     Yes   392.48
5   Male    6     No    438.21
6   Male    6     Yes   782.68

Is that what you want?

     Sex       Children Smoker  size mean
0     Female       1    No      1   58.32
1     Female       1    Yes     1   125.98
2     Female       4    No      1   356.12
3     Female       4    Yes     1   585.12
4       Male       3    Yes     1   392.48
5       Male       6    No      1   438.21
6       Male       6    Yes     1   782.68