在pandas中，如何从基于另一个数据框的数据框中删除行？

Question

我有2个数据框，一个命名为USERS，另一个命名为EXCLUDE。他们两个都有一个名为“电子邮件”的字段。

基本上，我要删除EXERSUDE中包含电子邮件的USERS中的每一行。

我该怎么做？

Answer 1

您可以将boolean indexing和条件一起使用isin，Series通过~以下方式反转布尔值：

import pandas as pd

USERS = pd.DataFrame({'email':['[e-mail]','[e-mail]','[e-mail]','[e-mail]','[e-mail]']})
print (USERS)
     email
0  [e-mail]
1  [e-mail]
2  [e-mail]
3  [e-mail]
4  [e-mail]

EXCLUDE = pd.DataFrame({'email':['[e-mail]','[e-mail]']})
print (EXCLUDE)
     email
0  [e-mail]
1  [e-mail]



print (USERS.email.isin(EXCLUDE.email))
0     True
1    False
2    False
3    False
4     True
Name: email, dtype: bool

print (~USERS.email.isin(EXCLUDE.email))
0    False
1     True
2     True
3     True
4    False
Name: email, dtype: bool

print (USERS[~USERS.email.isin(EXCLUDE.email)])
     email
1  [e-mail]
2  [e-mail]
3  [e-mail]

另一个解决方案merge：

df = pd.merge(USERS, EXCLUDE, how='outer', indicator=True)
print (df)
     email     _merge
0  [e-mail]       both
1  [e-mail]  left_only
2  [e-mail]  left_only
3  [e-mail]  left_only
4  [e-mail]       both

print (df.loc[df._merge == 'left_only', ['email']])
     email
1  [e-mail]
2  [e-mail]
3  [e-mail]