只需将两列相乘：
In [11]: df_city['weighted_jobs'] = df_city['weight'] * df_city['jobs']
现在您可以按城市分组（并取总和）：
In [12]: df_city_sums = df_city.groupby('city').sum()
In [13]: df_city_sums
Out[13]:
jobs weight weighted_jobs
city
oakland 362 690 7958
san mateo 367 1017 9026
sf 253 638 6209
[3 rows x 3 columns]
现在，您可以将两个和除，以获得所需的结果：
In [14]: df_city_sums['weighted_jobs'] / df_city_sums['jobs']
Out[14]:
city
oakland 21.983425
san mateo 24.594005
sf 24.541502
dtype: float64
602392714
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