Question

我想创建一个带有条件的字符串新列。示例：

from pandas import DataFrame
GoT = {'Old_Group': ['Jon Snow', 'Sansa Stark','Arya Stark','Robb Stark','Theon Greyjoy' ]}
df = DataFrame(GoT,columns=['Old_Group'])

“ New_Group”应检查“ Old_Group”是否在任意位置包含字符串“ Stark”，并将其分配给例如“斯塔克家族”。如果条件“包含=‘斯塔克’”不适合，那么“new_group”应当被分配给例如“其他”

在SQL中，我会这样做：

Select Old_Group
,case when Old_Group like '%Stark%' then 'Stark Family' else 'other' end as New_Group
from df

谢谢

Answer 1

您可以结合使用np.where和str.contains来执行此操作。从本质上讲，您不能执行的操作是在相关列上使用np.where（在本例中为Old Group），然后检查字符串是否包含工作Stark。

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只需确保您的“新建组”列为字符串数据类型，并且已将numpy导入为包

Answer 2

如果名称Stark以MacStark之类的名称出现，则此选项将其排除在外。也是不区分大小写的

df.assign(New_Column=df.replace({r'(?i)^((?!\bStark\b).)*$':'Other',r'(?i)\bStark\b':'Stark Family'},regex=True))
Out[319]: 
       Old_Group          New_Column
0       Jon Snow               Other
1    Sansa Stark  Sansa Stark Family
2     Arya Stark   Arya Stark Family
3     Robb Stark   Robb Stark Family
4  Theon Greyjoy               Other

Answer 3

您需要：

    (SELECT model, price FROM PC) NATURAL JOIN (SELECT model FROM Product WHERE maker='B')

    UNION

    (SELECT model, price FROM Laptop) NATURAL JOIN (SELECT model FROM Product WHERE maker='B')

    UNION

    (SELECT model, price FROM Printer) NATURAL JOIN (SELECT model FROM Product WHERE maker='B');

输出

df['New_Group'] = df['Old_Group'].apply(lambda x : 'Stark Family' if 'Stark' in x else 'other')

print(df)

Python：使用条件和“包含”语句创建新列

3 个答案: