我想加入兩個資料框df1和df2兩列。例如，在以下資料框中，我想將它們與列 a、b 和 a1、b1 連接起來，并構建第三個資料框。
import pandas as pd
import numpy as np
df1 = pd.DataFrame()
df2 = pd.DataFrame()
df3 = pd.DataFrame()
df1['a'] = [ 1, 2, 3 ]
df1['b'] = [ 2, 4, 6]
df1['c'] = [ 3, 5, 9]
df2['a1'] = [ 1, 2 ]
df2['b1'] = [ 4, 4]
df2['c1'] = [ 7, 5]
輸出：
uj5u.com熱心網友回復：
您可以使用pd.merge()and 多個鍵a, band a1,b1使用left_onand right_on, 如下：
import pandas as pd
import numpy as np
df1 = pd.DataFrame()
df2 = pd.DataFrame()
df3 = pd.DataFrame()
df1['a'] = [1, 2, 3]
df1['b'] = [2, 4, 6]
df1['c'] = [3, 5, 9]
df2['a1'] = [1, 2]
df2['b1'] = [4, 4]
df2['c1'] = [7, 5]
df3 = pd.merge(df1, df2, left_on=['a', 'b'], right_on=['a1', 'b1'], how='inner')
print(df3) # df3 has all columns for df1 and df2
# a b c a1 b1 c1
#0 2 4 5 2 4 5
df3 = df3.drop(df2.columns, axis=1) # removed columns of df2 as they're duplicated
df3.columns = ['a2', 'b2', 'c3'] # column names are changed as you want.
print(df3)
# a2 b2 c3
#0 2 4 5
有關更多資訊pd.merge()，請參閱：https ://pandas.pydata.org/docs/reference/api/pandas.merge.html
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