Python 基于条件合并来自Pandas Dataframe的结果列

我有两个数据帧如下

df1 = pd.DataFrame( {
    "names": ['alpha', 'bravo', 'charlie', 'delta', 'echo', 'foxtrot', 'golf'],
    "Debit": [0, 5000, 0, 5000, 3000, 0, 700],
    "Credit": [1000, 0, 2000, 0, 0, 8000, 0],
} )

和

df2 = pd.DataFrame( {
    "names": ['alpha', 'bravo', 'charlie', 'delta', 'echo', 'foxtrot'],
    "db_head": [1, 1, 1, 1, 1, 1],
    "cr_head": [2, 2, 2, 2, 2, 2],
} )

我想要的输出是:

     names  Debit  Credit   head
0    alpha      0    1000      2
1    bravo   5000       0      1
2  charlie      0    2000      2
3    delta   5000       0      1
4     echo   3000       0      1
5  foxtrot      0    8000      2

I tried to merge but did not underst和 how to get the value from two of the last columns based on the current df's column values

如果无条件合并

print(df1.merge(df2, how="inner", on="names"))

通过简单地合并这两个数据帧，结果如下

     names  Debit  Credit  db_head  cr_head
0    alpha      0    1000        1        2
1    bravo   5000       0        1        2
2  charlie      0    2000        1        2
3    delta   5000       0        1        2
4     echo   3000       0        1        2
5  foxtrot      0    8000        1        2

我try 了这两种方法，但这两种方法都有错误

df1['acchead'] = [df2[df2['names'] == x].db_head.item() if y > 0 else df2[df2['names'] == x].cr_head.item() for x, y in [df1['names'], df1['Debit']]]

df1['acchead'] = [df2[df2['names'] == x].db_head.item() if df1.Debit.item() > 0 else df2[df2['names'] == x].cr_head.item() for x in [df1['names']]]

任何帮助都将不胜感激.