文章目录

前言

根据 莫烦Python的教程 总结写成，以便自己复习和使用,这里我就不哟林地挂原创了🐶。

参数on

on：以列为索引进行合并

left = pd.DataFrame({'key':['K0','K1','K2','K3'],'A':['A0','A1','A2','A3'],'B':['B0','B1','B2','B3']})right = pd.DataFrame({'key':['K0','K1','K2','K3'],'C':['C0','C1','C2','C3'],'D':['D0','D1','D2','D3']})res = pd.merge(left,right,on=['key1','key2'],how='left') # how = inner：党同伐异；outer：求同存异；right：以第二个参数即right的'key1','key2'为准，得到的结果包含所有的'key1','key2'值，left：同理

参数 index

index：以行为索引进行合并

left = pd.DataFrame({'A':['A0','A1','A2'],'B':['B0','B1','B2']},index=['K0','K1','K2'])right = pd.DataFrame({'C':['C0','C1','C2'],'D':['D0','D1','D2']},index=['K0','K2','K3'])res = pd.merge(left,right,left_index=True,right_index=True,how='outer')

参数indicator

indicator 显示数据是按照哪种规则合成

df1 = pd.DataFrame({'col1':[0,1],'col_left':['a','b']})df2 = pd.DataFrame({'col1':[1,2,2],'col_right':[2,2,2]})res = pd.merge(df1,df2,on='col1',how='outer',indicator='indicator')

参数 suffixes

给合并后的数据加上后缀以区分不同的数据

boys = pd.DataFrame({'k':['K0','K1','K2'],'age':[1,2,3]})girls = pd.DataFrame({'k':['K0','K0','K3'],'age':[4,5,6]})res = pd.merge(boys,girls,on='k',suffixes=['_boy','_girl'],how='inner')