How to join two dataframes for which column values are within a certain range?

Given two dataframes df_1 and df_2, how to join them such that datetime column df_1 is in between start and end in dataframe df_2:

    print df_1

      timestamp              A          B
    0 2016-05-14 10:54:33    0.020228   0.026572
    1 2016-05-14 10:54:34    0.057780   0.175499
    2 2016-05-14 10:54:35    0.098808   0.620986
    3 2016-05-14 10:54:36    0.158789   1.014819
    4 2016-05-14 10:54:39    0.038129   2.384590


    print df_2

      start                end                  event    
    0 2016-05-14 10:54:31  2016-05-14 10:54:33  E1
    1 2016-05-14 10:54:34  2016-05-14 10:54:37  E2
    2 2016-05-14 10:54:38  2016-05-14 10:54:42  E3

Get corresponding event where df1.timestamp is between df_2.start and df2.end

      timestamp              A          B          event
    0 2016-05-14 10:54:33    0.020228   0.026572   E1
    1 2016-05-14 10:54:34    0.057780   0.175499   E2
    2 2016-05-14 10:54:35    0.098808   0.620986   E2
    3 2016-05-14 10:54:36    0.158789   1.014819   E2
    4 2016-05-14 10:54:39    0.038129   2.384590   E3

One simple solution is create interval index from start and end setting closed = both then use get_loc to get the event i.e (Hope all the date times are in timestamps dtype )

    df_2.index = pd.IntervalIndex.from_arrays(df_2['start'],df_2['end'],closed='both')
    df_1['event'] = df_1['timestamp'].apply(lambda x : df_2.iloc[df_2.index.get_loc(x)]['event'])

Output :

                timestamp         A         B event
    0 2016-05-14 10:54:33  0.020228  0.026572    E1
    1 2016-05-14 10:54:34  0.057780  0.175499    E2
    2 2016-05-14 10:54:35  0.098808  0.620986    E2
    3 2016-05-14 10:54:36  0.158789  1.014819    E2
    4 2016-05-14 10:54:39  0.038129  2.384590    E3

From: stackoverflow.com/q/46525786