将条件值从一列复制到另一列

Question

给定这样的df：

Date          Category  Debit     Credit
2020-01-05    Utility   55.32     NA
2020-01-05    Movie     20.01     NA
2020-01-05    Payment   NA        -255.32
2020-01-05    Grocery   97.64     NA

如何将所有负信用值移动到借方列（并删除空的信用列）？

Date          Category  Debit     
2020-01-05    Utility   55.32    
2020-01-05    Movie     20.01    
2020-01-05    Payment   -255.32        
2020-01-05    Grocery   97.64    

这将找到负值：

df.loc[df['Credit'] < 0]

但这不起作用（最小的 pandas 技能）

def creditmover():
    If df.loc[df['Credit'] < 0]:
        df.loc[df['Debit']]=df.loc[df['Credit']]

谢谢！

Answer 1

根据你的逻辑，你可以这样做：

# where credit is < 0
s = df['Credit'] < 0

# copy the corresponding values
df.loc[s, 'Debit'] = df.loc[s, 'Credit']

# drop Credit
df = df.drop('Credit', axis=1)

Output：

         Date Category   Debit
0  2020-01-05  Utility   55.32
1  2020-01-05    Movie   20.01
2  2020-01-05  Payment -255.32
3  2020-01-05  Grocery   97.64

注意：如果在Credit <0的情况下， Debit始终为Na ，反之亦然，那么您可以简单地执行以下操作：

df['Debit'] = df['Debit'].fillna(df['Credit'])

df = df.drop('Credit', axis=1)

Answer 2

我们可以做pop

df.loc[df.pop('Credit')<=0,'Debit']=df.Credit
df
         Date Category   Debit
0  2020-01-05  Utility   55.32
1  2020-01-05    Movie   20.01
2  2020-01-05  Payment -255.32
3  2020-01-05  Grocery   97.64