Python Column Generation with AVERAGEIF equivalent to Excel [duplicate]

问题

This question already has answers here:

Pandas: using groupby to get mean for each data category (2 answers)

Closed 2 years ago.

I've poured over StackOverflow and just cant figure this one out. I a data tables with unique letter# combinations, and im trying to get the "averageif" of those values into the second table. Basically, I am trying to generate the "AVG" column below.

Letter  Value      Unique   Avg
A1  7.97           A1       5.76
A1  3.56           A2       5.34 
A2  3.16           A3       1.53
A2  9.09           B1       4.55
A2  0.64           B2       5.43
A2  8.48           B3       6.76
A3  1.53
B1  4.55
B2  7.36
B2  3.81
B2  7.30
B2  4.39
B2  4.30
B3  4.61
B3  8.91

I've used pd.DataFrame to isolate the unique values in the first data set as a DataFrame of unique values, but I'm really having trouble. I have all the code to pull this data in from a csv, generate the unique values, etc but it doesnt seem relevant. Thanks for any advice, I just cant get passed this step.

Best

回答1:

Well, you can do that using groupby as follows:

df.groupby('Letter').mean()

来源：https://stackoverflow.com/questions/47336754/python-column-generation-with-averageif-equivalent-to-excel