How to calculate time difference for each id between current row and next for dataset below:
time id
2012-03-16 23:50:00 1
2012-03-16 23:56:00 1
2012-03-17 00:08:00 1
2012-03-17 00:10:00 2
2012-03-17 00:12:00 2
2012-03-17 00:20:00 2
2012-03-20 00:43:00 3
and get next result:
time id tdiff
2012-03-16 23:50:00 1 6
2012-03-16 23:56:00 1 12
2012-03-17 00:08:00 1 NA
2012-03-17 00:10:00 2 2
2012-03-17 00:12:00 2 8
2012-03-17 00:20:00 2 NA
2012-03-20 00:43:00 3 NA
I see that you need result in minutes by id. Here is how to do it :
use diff() in groupby :
# first convert to datetime with the right format
data['time']=pd.to_datetime(data.time, format='%Y-%m-%d %H:%M:%S')
data['tdiff']=(data.groupby('id').diff().time.values/60000000000).astype(int)
data['tdiff'][data['tdiff'] < 0] = np.nan
print(data)
output
time id tdiff
0 2012-03-16 23:50:00 1 NaN
1 2012-03-16 23:56:00 1 6.0
2 2012-03-17 00:08:00 1 12.0
3 2012-03-17 00:10:00 2 NaN
4 2012-03-17 00:12:00 2 2.0
5 2012-03-17 00:20:00 2 8.0
6 2012-03-20 00:43:00 3 NaN