Python Pandas – merge 函數

測試環境為 CentOS 8 (虛擬機)

merge 函數就跟 SQL join 依樣可以將兩個資料表依據相對應的資料欄位合併起來.

安裝所需模組

[root@localhost ~]# pip install pandas

匯入模組

[root@localhost ~]# python3
Python 3.6.8 (default, Sep 10 2021, 09:13:53)
[GCC 8.5.0 20210514 (Red Hat 8.5.0-3)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pandas as pd

參考範例 – https://levelup.gitconnected.com/20-pandas-functions-for-80-of-your-data-science-tasks-b610c8bfe63c

>>> df1 = pd.DataFrame({'key': ['A', 'B', 'C', 'D'],
...                    'value': [1, 2, 3, 4]})
>>> df1
  key  value
0   A      1
1   B      2
2   C      3
3   D      4

>>> df2 = pd.DataFrame({'key': ['B', 'D', 'E', 'F'],
...                    'value': [5, 6, 7, 8]})
>>> df2
  key  value
0   B      5
1   D      6
2   E      7
3   F      8

依據 key 欄位來合併.

>>> merged_df = df1.merge(df2, on='key')
>>> merged_df
  key  value_x  value_y
0   B        2        5
1   D        4        6