【pandas】条件查询 分组标记

对符合 条件 的数据进行标记

数据如下：

import pandas as pd
import numpy as np 
data=[['Amy',13],['Susan',19],['Tom',14],['Ella',18]]
df = pd.DataFrame(data,columns=['Name','Age'])
df

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	Name	Age
0	Amy	13
1	Susan	19
2	Tom	14
3	Ella	18

如果 age>18, 则在adult（成年人）列，显示Yes，否则显示No

df['adult']=np.where(df['Age']>=18,'Yes','No')
df

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	Name	Age	adult
0	Amy	13	No
1	Susan	19	Yes
2	Tom	14	No
3	Ella	18	Yes

对符合多个条件的数据进行分组标记

数据如下：

data=[['Beijing',4000],['ShangHai',5000],['Beijing',3500],['Nanjing',2000],['Beijing',3800]]
df1=pd.DataFrame(data,columns=['city','price'])
df1

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	city	price
0	Beijing	4000
1	ShangHai	5000
2	Beijing	3500
3	Nanjing	2000
4	Beijing	3800

如果city是Beijin,且price大于等于3800，则标记为1

df1.loc[(df1['city']=='Beijing') & (df1['price']>=3800),'sing']=1
df1

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	city	price	sing
0	Beijing	4000	1.0
1	ShangHai	5000	NaN
2	Beijing	3500	NaN
3	Nanjing	2000	NaN
4	Beijing	3800	1.0