Pandas dataframe，如何创建一个新的总计列，其中包含基于其他列的值

Question

>>> df

         Dr Name           Type   Total  Fund Total
0        Debtors  Balance Sheet  200.00        0.00
1           Bank  Balance Sheet  352.25      100.00
4   General Fund           Fund -100.00     -252.25
5  Building Fund           Fund    0.00     -300.00

I want a new column to be created, being filled with either Totals or Fund Totals.

If the Type is Balance Sheet I would like the Total column to be used - and if the Type is Fund the Fund Total to be used. To produce this:

>>> df

         Dr Name           Type   Total  Fund Total   Grand Total
0        Debtors  Balance Sheet  200.00        0.00        200.00
1           Bank  Balance Sheet  352.25      100.00        352.25
4   General Fund           Fund -100.00     -252.25       -252.25
5  Building Fund           Fund    0.00     -300.00       -300.00

Thanks

Answer 1

This is a possible solution:

df["Grand Total"] = df.where(df["Type"] == "Fund")["Fund Total"].fillna(df["Total"])

With df.where I extract the column Fund Total only where the type is Fund (other rows will be nan . Then fillna fills those nan using another column ( Total in this case)

Answer 2

Another way is to use where from numpy :

import panda as pd

df['Grand Total'] = np.where(df['Type'] == 'Fund', df['Fund Total'], df['Total'])
print(df)

# Output
         Dr Name           Type   Total  Fund Total  Grand Total
0        Debtors  Balance Sheet  200.00        0.00       200.00
1           Bank  Balance Sheet  352.25      100.00       352.25
4   General Fund           Fund -100.00     -252.25      -252.25
5  Building Fund           Fund    0.00     -300.00      -300.00