Try this:
x$Timestamp <- as.POSIXct(strptime(as.character(x$Timestamp), "%d/%m/%y
%H:%M"))
x$time <- as.numeric(x$Timestamp > as.POSIXct(strptime("07-08-2008 00:00",
"%d-%m-%Y %H:%M")))
with(x, tapply(Timestamp, user_id, function(x)diff(range(x), units="secs"),
simplify = F))
On Mon, Oct 13, 2008 at 7:57 AM, Michael Pearmain <[EMAIL PROTECTED]>wrote:
> 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
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
--
Henrique Dallazuanna
Curitiba-Paraná-Brasil
25° 25' 40" S 49° 16' 22" O
[[alternative HTML version deleted]]
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