Subtract pandas columns from a specified column

六眼飞鱼酱① 提交于 2019-12-01 04:49:45

问题


How can I dynamically subtract values in multiple pandas dataframe columns from a specified column. In this case, how can I subtract columns A, B, and C from deposit and place the value in the corresponding A, B, and C columns.

   date         deposit       A                 B           C
0  2017-01-15   12            5                 10          12
1  2017-01-16   20            10                4           32
2  2017-01-17   5             50                10          18
3  2017-01-18   22            15                20          12

should produce:

   date         deposit       A                 B           C
0  2017-01-15   12            7                 2           0
1  2017-01-16   20            10                16         -12
2  2017-01-17   5            -45               -5          -13
3  2017-01-18   22            7                 2           10

回答1:


In [226]: df[['A','B','C']] = df.deposit.values[:, None] - df[['A','B','C']]

In [227]: df
Out[227]:
         date  deposit   A   B   C
0  2017-01-15       12   7   2   0
1  2017-01-16       20  10  16 -12
2  2017-01-17        5 -45  -5 -13
3  2017-01-18       22   7   2  10



回答2:


loc + rsub

cols = ['A', 'B', 'C']
df.loc[:, cols] = df[cols].rsub(df.deposit, 0)
df


         date  deposit   A   B   C
0  2017-01-15       12   7   2   0
1  2017-01-16       20  10  16 -12
2  2017-01-17        5 -45  -5 -13
3  2017-01-18       22   7   2  10

inplace
My preference for doing it inplace

df.update(df[['A', 'B', 'C']].rsub(df.deposit, 0))

df

         date  deposit   A   B   C
0  2017-01-15       12   7   2   0
1  2017-01-16       20  10  16 -12
2  2017-01-17        5 -45  -5 -13
3  2017-01-18       22   7   2  10

copy
My preference overall

df.assign(**df[['A', 'B', 'C']].rsub(df.deposit, 0).to_dict('list'))

         date  deposit   A   B   C
0  2017-01-15       12   7   2   0
1  2017-01-16       20  10  16 -12
2  2017-01-17        5 -45  -5 -13
3  2017-01-18       22   7   2  10



回答3:


for c in ['A','B','C']:
    df[c]=df['deposit']-df[c]


来源:https://stackoverflow.com/questions/43770401/subtract-pandas-columns-from-a-specified-column

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