#合并多个数据集
#合并: 关系型数据库中的两个表之间的连接
#table1.field1 table2.field2 select table1.field1,table2.field2 from table1,table2 where table1.field1 = table2.field2
#1. 一对一
#2. 多对一
#3. 多对多
import pandas as pd
person = pd.read_csv('./data/survey_person.csv')
site = pd.read_csv('./data/survey_site.csv')
survey = pd.read_csv('./data/survey_survey.csv')
visited = pd.read_csv('./data/survey_visited.csv')
print(person)
print(site)
print(visited)
print(survey)
#取行
visited_subset = visited.loc[[0,2,6],]
print(visited_subset)
#一对一连接
#参与连接的字段或者列名 --left_on、right_on left_on的结果集是site 右边结果集是right_on
merge1 = site.merge(visited_subset,left_on ='name',right_on = 'site')
print(merge1)
#多对一
merge2 = site.merge(visited,left_on='name',right_on='site')
print(merge2)
#多对多
ps = person.merge(survey,left_on='ident',right_on='person')
vs = visited.merge(survey,left_on = 'ident',right_on = 'taken')
print(ps)
print(vs)
(venv) E:\py3>python py21.py
ident personal family
0 dyer William Dyer
1 pb Frank Pabodie
2 lake Anderson Lake
3 roe Valentina Roerich
4 danforth Frank Danforth
name lat long
0 DR-1 -49.85 -128.57
1 DR-3 -47.15 -126.72
2 MSK-4 -48.87 -123.40
ident site dated
0 619 DR-1 1927-02-08
1 622 DR-1 1927-02-10
2 734 DR-3 1939-01-07
3 735 DR-3 1930-01-12
4 751 DR-3 1930-02-26
5 752 DR-3 NaN
6 837 MSK-4 1932-01-14
7 844 DR-1 1932-03-22
taken person quant reading
0 619 dyer rad 9.82
1 619 dyer sal 0.13
2 622 dyer rad 7.80
3 622 dyer sal 0.09
4 734 pb rad 8.41
5 734 lake sal 0.05
6 734 pb temp -21.50
7 735 pb rad 7.22
8 735 NaN sal 0.06
9 735 NaN temp -26.00
10 751 pb rad 4.35
11 751 pb temp -18.50
12 751 lake sal 0.10
13 752 lake rad 2.19
14 752 lake sal 0.09
15 752 lake temp -16.00
16 752 roe sal 41.60
17 837 lake rad 1.46
18 837 lake sal 0.21
19 837 roe sal 22.50
20 844 roe rad 11.25
ident site dated
0 619 DR-1 1927-02-08
2 734 DR-3 1939-01-07
6 837 MSK-4 1932-01-14
name lat long ident site dated
0 DR-1 -49.85 -128.57 619 DR-1 1927-02-08
1 DR-3 -47.15 -126.72 734 DR-3 1939-01-07
2 MSK-4 -48.87 -123.40 837 MSK-4 1932-01-14
(venv) E:\py3>python py21.py
ident personal family
0 dyer William Dyer
1 pb Frank Pabodie
2 lake Anderson Lake
3 roe Valentina Roerich
4 danforth Frank Danforth
name lat long
0 DR-1 -49.85 -128.57
1 DR-3 -47.15 -126.72
2 MSK-4 -48.87 -123.40
ident site dated
0 619 DR-1 1927-02-08
1 622 DR-1 1927-02-10
2 734 DR-3 1939-01-07
3 735 DR-3 1930-01-12
4 751 DR-3 1930-02-26
5 752 DR-3 NaN
6 837 MSK-4 1932-01-14
7 844 DR-1 1932-03-22
taken person quant reading
0 619 dyer rad 9.82
1 619 dyer sal 0.13
2 622 dyer rad 7.80
3 622 dyer sal 0.09
4 734 pb rad 8.41
5 734 lake sal 0.05
6 734 pb temp -21.50
7 735 pb rad 7.22
8 735 NaN sal 0.06
9 735 NaN temp -26.00
10 751 pb rad 4.35
11 751 pb temp -18.50
12 751 lake sal 0.10
13 752 lake rad 2.19
14 752 lake sal 0.09
15 752 lake temp -16.00
16 752 roe sal 41.60
17 837 lake rad 1.46
18 837 lake sal 0.21
19 837 roe sal 22.50
20 844 roe rad 11.25
ident site dated
0 619 DR-1 1927-02-08
2 734 DR-3 1939-01-07
6 837 MSK-4 1932-01-14
name lat long ident site dated
0 DR-1 -49.85 -128.57 619 DR-1 1927-02-08
1 DR-3 -47.15 -126.72 734 DR-3 1939-01-07
2 MSK-4 -48.87 -123.40 837 MSK-4 1932-01-14
name lat long ident site dated
0 DR-1 -49.85 -128.57 619 DR-1 1927-02-08
1 DR-1 -49.85 -128.57 622 DR-1 1927-02-10
2 DR-1 -49.85 -128.57 844 DR-1 1932-03-22
3 DR-3 -47.15 -126.72 734 DR-3 1939-01-07
4 DR-3 -47.15 -126.72 735 DR-3 1930-01-12
5 DR-3 -47.15 -126.72 751 DR-3 1930-02-26
6 DR-3 -47.15 -126.72 752 DR-3 NaN
7 MSK-4 -48.87 -123.40 837 MSK-4 1932-01-14
ident personal family taken person quant reading
0 dyer William Dyer 619 dyer rad 9.82
1 dyer William Dyer 619 dyer sal 0.13
2 dyer William Dyer 622 dyer rad 7.80
3 dyer William Dyer 622 dyer sal 0.09
4 pb Frank Pabodie 734 pb rad 8.41
5 pb Frank Pabodie 734 pb temp -21.50
6 pb Frank Pabodie 735 pb rad 7.22
7 pb Frank Pabodie 751 pb rad 4.35
8 pb Frank Pabodie 751 pb temp -18.50
9 lake Anderson Lake 734 lake sal 0.05
10 lake Anderson Lake 751 lake sal 0.10
11 lake Anderson Lake 752 lake rad 2.19
12 lake Anderson Lake 752 lake sal 0.09
13 lake Anderson Lake 752 lake temp -16.00
14 lake Anderson Lake 837 lake rad 1.46
15 lake Anderson Lake 837 lake sal 0.21
16 roe Valentina Roerich 752 roe sal 41.60
17 roe Valentina Roerich 837 roe sal 22.50
18 roe Valentina Roerich 844 roe rad 11.25
ident site dated taken person quant reading
0 619 DR-1 1927-02-08 619 dyer rad 9.82
1 619 DR-1 1927-02-08 619 dyer sal 0.13
2 622 DR-1 1927-02-10 622 dyer rad 7.80
3 622 DR-1 1927-02-10 622 dyer sal 0.09
4 734 DR-3 1939-01-07 734 pb rad 8.41
5 734 DR-3 1939-01-07 734 lake sal 0.05
6 734 DR-3 1939-01-07 734 pb temp -21.50
7 735 DR-3 1930-01-12 735 pb rad 7.22
8 735 DR-3 1930-01-12 735 NaN sal 0.06
9 735 DR-3 1930-01-12 735 NaN temp -26.00
10 751 DR-3 1930-02-26 751 pb rad 4.35
11 751 DR-3 1930-02-26 751 pb temp -18.50
12 751 DR-3 1930-02-26 751 lake sal 0.10
13 752 DR-3 NaN 752 lake rad 2.19
14 752 DR-3 NaN 752 lake sal 0.09
15 752 DR-3 NaN 752 lake temp -16.00
16 752 DR-3 NaN 752 roe sal 41.60
17 837 MSK-4 1932-01-14 837 lake rad 1.46
18 837 MSK-4 1932-01-14 837 lake sal 0.21
19 837 MSK-4 1932-01-14 837 roe sal 22.50
20 844 DR-1 1932-03-22 844 roe rad 11.25
来源：CSDN
作者：dajiahao
链接：https://blog.csdn.net/u012164509/article/details/101768259