pandas连接查询

news2024/11/23 9:02:51

df1数据如下

在这里插入图片描述

df2数据如下

在这里插入图片描述

连接查询代码 -1

import pandas as pd

df1 = pd.DataFrame({'id':['1001','1002','1003','1004'],
                      'name':['Hu','Dotu','Evp','Swe']})
df2 = pd.DataFrame({'id':['1001','1001','1003','1004', '1003'],
                      'course':['c1','c2','c3','c2','c1'],
                      'score':[100, 98, 64, 84, 69]})

result = pd.merge(df1, df2, how='right',on = 'id')

print('========= result =========')    # 效果如下
print(result)

运行结果

========= result =========
     id name course  score
0  1001   Hu     c1    100
1  1001   Hu     c2     98
2  1003  Evp     c3     64
3  1004  Swe     c2     84
4  1003  Evp     c1     69

在这里插入图片描述

连接查询代码 -2

import pandas as pd

df1 = pd.DataFrame({'id':['1001','1002','1003','1004'],
                      'name':['Hu','Dotu','Evp','Swe']})
df2 = pd.DataFrame({'id':['1001','1001','1003','1004', '1003'],
                      'course':['c1','c2','c3','c2','c1'],
                      'score':[100, 98, 64, 84, 69]})

result = pd.merge(df1, df2, how='left',on = 'id')

print('========= result =========')    # 效果如下
print(result)

运行结果

     id  name course  score
0  1001    Hu     c1  100.0
1  1001    Hu     c2   98.0
2  1002  Dotu    NaN    NaN
3  1003   Evp     c3   64.0
4  1003   Evp     c1   69.0
5  1004   Swe     c2   84.0

在这里插入图片描述