pandas join consecutive rows group by timedelta64[ns] column

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I have a dataframe:

data = {'process': ['buying','selling','searhicng','repairing', 'preparing', 'selling','buying', 'searching', 'selling','searching'],
        'type': ['in_progress','in_progress','end','in_progress', 'end', 'in_progress','in_progress', 'end', 'in_progress','end'],
'country': ['usa',np.nan, 'usa','ghana', np.nan,'end','portugal', np.nan, np.nan,'england'],
'id': ['022','022','022', '011','011', '011','011', '011', '011','011'],
        'lag': ['00:00:10.042721','00:00:00.042721','00:00:05.042721','00:10:00.042721','00:00:00.042721','00:00:00.042721','00:00:50.042721','00:00:00.042721','00:00:00.042721','00:00:00.042721'],
        'created': ['2021-07-01','2021-07-02','2021-07-03','2021-07-04','2021-07-05','2021-07-06','2021-07-06','2021-07-08','2021-07-09','2021-07-10'],
        'next_created': ['2021-07-01','2021-07-02','2021-07-03','2021-07-04','2021-07-05','2021-07-06','2021-07-07','2021-07-08','2021-07-09','2021-07-10']
}
df = pd.DataFrame(data, columns = ['process','type','country', 'id','lag','created','next_created'])

enter image description here

I need to concatenate consecutive rows by the process column for each group by id, which have lag less than one second, write the value of the first row to created, and created_next the value of the last line.

Can anyone see the problem, i don't understand how i can use groupby in this situation.

I guess that i need to use cumsum(), but i don't know what i can use in the ??? place

df['lag'].shift(1).???.cumsum()

Output result

enter image description here

pandas dataframe python
1 Answers

You can try:

# Convert to timedelta to facilitate checking of within one second
df['lag'] = pd.to_timedelta(df['lag'])

# Grouping by `lag` difference is less than one second within the same `id`
group = df['lag'].diff().abs().gt(np.timedelta64(1, 's')).groupby(df['id']).cumsum()

# Group by `id` and newly created grouping and then aggregate
(df.groupby(['id', group], as_index=False, sort=False)
   .agg({'process': lambda x: ' '.join(x),   # concatenate consecutive rows within total grouping
         'type': 'first',
         'country': lambda x: x.iloc[0],     # get first entry including `NaN`
         'id': 'first',
         'lag': 'first',
         'created': 'first',                 # get first entry 
         'next_created': 'last'              # get last entry   
        })
)

Result:

                       process         type   country   id                    lag     created next_created
0                       buying  in_progress       usa  022 0 days 00:00:10.042721  2021-07-01   2021-07-01
1                      selling  in_progress       NaN  022 0 days 00:00:00.042721  2021-07-02   2021-07-02
2                    searhicng          end       usa  022 0 days 00:00:05.042721  2021-07-03   2021-07-03
3                    repairing  in_progress     ghana  011 0 days 00:10:00.042721  2021-07-04   2021-07-04
4            preparing selling          end       NaN  011 0 days 00:00:00.042721  2021-07-05   2021-07-06
5                       buying  in_progress  portugal  011 0 days 00:00:50.042721  2021-07-06   2021-07-07
6  searching selling searching          end       NaN  011 0 days 00:00:00.042721  2021-07-08   2021-07-10
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