熊猫：如何根据列内容的不同组合分配多个值？

Question

我想基于以下条件创建一个具有数值的新列：

一个。如果color = blue＆amp; pet = dog，points = 10

湾如果color = blue＆amp; pet = cat，points = 8

℃。如果pet = snake＆amp;性别=女性，分数= 7

d。如果pet = mouse＆amp;性别=男性，分数= 6

所有行都必须满足其中一个条件。这些行永远不会满足2个条件。

    color     pet       gender
0   blue      dog       male
1   blue      cat       male
2   orange    snake     female
3   green     mouse     male

我希望最终结果如下：

    color     pet       gender     points
0   blue      dog       male       10
1   blue      cat       male       8
2   orange    snake     female     7
3   green     mouse     male       6

我如何做到这一点？

Answer 1

我认为使用loc掩盖的4个独立作业可能更具可读性，而不是做一个很长的单行，

In [4]:
df.loc[(df['color']=='blue') & (df['pet']=='dog'), 'points'] = 10
df.loc[(df['color']=='blue') & (df['pet']=='cat'), 'points'] = 8
df.loc[(df['pet']=='snake') & (df['gender']=='female'), 'points'] = 7    
df.loc[(df['pet']=='mouse') & (df['gender']=='male'), 'points'] = 6
df

Out[4]:

    color    pet  gender  points
0    blue    dog    male      10
1    blue    cat    male       8
2  orange  snake  female       7
3   green  mouse    male       6

将上述内容重写为多嵌套np.where语句是可能的，但我发现一旦你达到3个以上的条件就会变得难以阅读，并且没有太多可以在单独的{{ {1}}陈述