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The following two dataframes:

df_t1 = pd.DataFrame({'Date' : [pd.Timestamp(2017, 1, 1), pd.Timestamp(2017, 1, 2), pd.Timestamp(2017, 1, 3)], 'A': [1, 2, 3]})
df_t1 = df_t1.set_index('Date')

df_t2 = pd.DataFrame({'Date' : [pd.Timestamp(2016, 12, 31), pd.Timestamp(2017, 1, 1), pd.Timestamp(2017, 1, 2), pd.Timestamp(2017, 1, 3), pd.Timestamp(2017, 1, 4)], 'C': [7, 8, 9, 10, 11]})
df_t2 = df_t2.set_index('Date')

can be merged like so

df_merge = df_t1.merge(df_t2, how='outer', left_on='Date', right_on='Date')

or like so

df_merge2 = df_t2.merge(df_t1, how='outer', left_on='Date', right_on='Date')

I expected both variants to return the df_merge2 as shown below, why is that not the case?

            C    A
Date
2016-12-31  7   NaN
2017-01-01  8   1.0
2017-01-02  9   2.0
2017-01-03  10  3.0
2017-01-04  11  NaN
Henrik K
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  • Just Check with concat https://stackoverflow.com/questions/49620538/what-are-the-levels-keys-and-names-arguments-for-in-pandas-concat-functio – BENY May 10 '19 at 15:21
  • `pd.concat([df_t1,df_t2],1) ` – BENY May 10 '19 at 15:23

0 Answers0