Python 我需要帮助找出如何仅在标识符键匹配的情况下更改数据帧中的值

假设我有两张桌子

第一

第二

我只想将表2中带有“u”的行的性别属性更改为表1中相应的性别

提前感谢您的帮助。

与left join一起使用，然后将

u

值替换为另一列的

\u

：

df2 = df2.merge(df1, on=['customer_id','first_name'], how='left', suffixes=('','_'))
df2['gender'] = df2['gender'].mask(df2['gender'] == 'u', df2.pop('gender_'))
print (df2)
  customer_id first_name  gender
0         3343  Cristabel  female
1         2469     Kermie    male
2          996       Aura  female
3         1628   Hermione  female
4         2696   Isabelle  female
5         1689       Jhon    male
6         5698     Albert    male

如果只想通过

customer\u id

进行匹配，而不是通过两列进行匹配，则可以选择：

mask = df2['gender'] == 'u'
s = df1.set_index('customer_id')['gender']
df2.loc[mask, 'gender'] = df2.loc[mask, 'customer_id'].map(s).fillna(df2['gender'])
print (df2)
   customer_id first_name  gender
0         3343  Cristabel  female
1         2469     Kermie    male
2          996       Aura  female
3         1628   Hermione  female
4         2696   Isabelle  female
5         1689       Jhon    male
6         5698     Albert    male

与left join一起使用，然后将

u

值替换为另一列为

\u

：

df2 = df2.merge(df1, on=['customer_id','first_name'], how='left', suffixes=('','_'))
df2['gender'] = df2['gender'].mask(df2['gender'] == 'u', df2.pop('gender_'))
print (df2)
  customer_id first_name  gender
0         3343  Cristabel  female
1         2469     Kermie    male
2          996       Aura  female
3         1628   Hermione  female
4         2696   Isabelle  female
5         1689       Jhon    male
6         5698     Albert    male

如果只想通过

customer\u id

进行匹配，而不是通过两列进行匹配，则可以选择：

mask = df2['gender'] == 'u'
s = df1.set_index('customer_id')['gender']
df2.loc[mask, 'gender'] = df2.loc[mask, 'customer_id'].map(s).fillna(df2['gender'])
print (df2)
   customer_id first_name  gender
0         3343  Cristabel  female
1         2469     Kermie    male
2          996       Aura  female
3         1628   Hermione  female
4         2696   Isabelle  female
5         1689       Jhon    male
6         5698     Albert    male

---

为什么这么复杂？一个简单的replace（）将do@Capie-因为您的解决方案与客户id、名字不匹配，所以wrong@jezrael您可以自己尝试，效果很好……@Capie check

Kermie

row，必须是

male

@jezrael哦，我以为表1是预期的结果，表2是输入…我的错…为什么这么复杂？一个简单的replace（）将do@Capie-因为您的解决方案与客户id、名字不匹配，所以wrong@jezrael您可以自己尝试，效果很好……@Capie check

Kermie

row，它必须是

male

@jezrael哦，我以为表1是预期结果，表2是输入……我的坏。。。