#Day 4+学习笔记+07/18
result = result.reset_index().rename(columns={"index":"cities"})
df4 = df4.reset_index().rename(columns={"index":"cities"})
pd.concat([result,df4], axis=1)
pd.merge(result, df4, axis=1)
pd.merge(result, df4, axis=1, on="cities", how="left") //按照参数 on 的值 cities 合并数据,效率比用index合并较低,how 可以选择保留哪一列数据的index值
df4 = df4.set_index("cities")
df1.join(df4,how="right")
pd.merge(df1, df4, left_index=True,right_index=True, how="outer")
pd.concat([df1, df4], axis=1, join_axes=[df1.index])
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