我正在嘗試向 Pandas GroupBy DataFrame 添加一列。新列(E) 是列(C) 上具有相同鍵(A,B) 的值的總和。該鍵由數(shù)據(jù)幀的另外兩列(A,B) 組成。This is my Dataframe A B C D0 foo one 1 15 1 bar one 2 10 2 foo two 4 20 3 bar three 4 5 4 foo two 5 6 5 bar two 6 9 6 foo one 7 8 7 foo three 8 15 what I want: A B C D E0 foo one 1 15 81 bar one 2 10 22 foo two 4 20 93 bar three 4 5 4 4 foo two 5 6 95 bar two 6 9 66 foo one 7 8 87 foo three 8 15 8這是我的代碼df = pd.DataFrame({'A' : ['foo', 'bar', 'foo', 'bar', ...: 'foo', 'bar', 'foo', 'foo'], ...: 'B' : ['one', 'one', 'two', 'three', ...: 'two', 'two', 'one', 'three'], ...: 'C' : ['1','2','4','4','5','6','7','8'], ...: 'D' : ['15','10','20','5','6','9','8','15']})我已經(jīng)嘗試過的df['E'] =df['C'].groupby(df['A,B']).transform('sum') 但不起作用
2 回答
婷婷同學(xué)_
TA貢獻(xiàn)1844條經(jīng)驗 獲得超8個贊
您可以通過 A 和 B 計算 C 的聚合總和，然后將結(jié)果數(shù)據(jù)幀與原始數(shù)據(jù)幀合并
>> df
A B C D
0 foo one 1 15
1 bar one 2 10
2 foo two 4 20
3 bar three 4 5
4 foo two 5 6
5 bar two 6 9
6 foo one 7 8
7 foo three 8 15
df2 = df.groupby(['A','B']).sum().drop(['D'], axis=1).rename(columns={'C':'E'})
>> df2
E
A B
bar one 2
three 4
two 6
foo one 8
three 8
two 9
合并df和df2可以得到結(jié)果：
>> df.merge(df2.reset_index(), on=['A', 'B'], how='left')
A B C D E
0 foo one 1 15 8
1 bar one 2 10 2
2 foo two 4 20 9
3 bar three 4 5 4
4 foo two 5 6 9
5 bar two 6 9 6
6 foo one 7 8 8
7 foo three 8 15 8
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