Hi All,
I've a couple of questions i've been struggling with using the time
features, can anyone help? sample data

               Timestamp            user_id
  27/05/08 22:57 763830873067  27/05/08 23:00 763830873067  27/05/08 23:01
763830873067  27/05/08 23:01 763830873067  05/06/08 11:34 763830873067
 29/05/08
23:08 765253440317  29/05/08 23:06 765253440317  29/05/08 22:52
765253440317  29/05/08
22:52 765253440317  29/05/08 23:04 765253440317  27/06/08 19:34
765253440317  09/07/08
15:45 765329002557  06/07/08 19:24 765329002557  09/07/08 15:46
765329002557  07/07/08
13:05 765329002557  16/05/08 22:40 765329002557  08/06/08 11:24
765329002557  08/06/08
12:33 765329002557

My first question is how can i create a new var creating a filter based on a
date?

I've tried as.POSIXct.strptime below as well but to no avail.. can anyone
give any advice?

>Mcookie$timestamp <- as.POSIXct(strptime(Mcookie$timestamp,"%m/%d/%Y
%H:%M"))
>Mcookie$time <- ifelse(Mcookie$timestamp >
strptime("07-08-2008-00:00","%m-%d-%Y-%H:%M",1,0)

My second questions refers to finding the time difference in seconds between
the first time a user sees something Vs the last.. and engagment time
essentially,
i see there is the difftime function,  is there a more elegant way of
working this out then my thoughts (Pysdo code below)

sort data by user_id and Timestamp
take the head of user_id as new_time_var
take the tail of user_id as new_time_var2
use difftime(new_time_var, new_time_var2, units="secs")

Mike

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