python的join

问题遇到的现象和发生背景

用代码块功能插入代码，请勿粘贴截图

我想要达到的结果

怎么不用merge函数用pandas的join函数来达到图片里的效果，既做出df3

join函数貌似无法做到这种效果

column1 = pd.Series(['a','b','c'],index=(range(3)))
column2 = pd.Series([0.63,0.19,0.02],index=(range(3)))
df1 = pd.DataFrame({"lkey":column1,"values1":column2})
column1 = pd.Series(['b', 'c','d'], index=(range(3)))
column2 = pd.Series([0.78, 0.31, 0.64], index=(range(3)))
df2 = pd.DataFrame({"rkey": column1, "values2": column2})
print(df1)
print(df2)
df = pd.merge(df1,df2,left_on="lkey",right_on="rkey",how="left")
print(df)

建议观看：
https://blog.csdn.net/weixin_43974265/article/details/104932709?ops_request_misc=&request_id=&biz_id=102&utm_term=python%E7%9A%84join&utm_medium=distribute.pc_search_result.none-task-blog-2~all~sobaiduweb~default-0-104932709.142^v62^js_top,201^v3^control_1,213^v1^control&spm=1018.2226.3001.4449