Hi,

I have a following data set:
id    event    time (in sec)
1     add      1373502892
2     add      1373502972
3     delete   1373502995
4     view      1373503896
5     add       1373503996
...

I'd like to add new column "time on task" which is time elapsed between two
events (id2 - id1...). What would be the best approach to do that?

Thanks,
Srecko

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