Try this:

findInterval(do.call(seq, c(as.list(as.POSIXct(DF$login_time)), by = '30
mins')), as.POSIXct(DF$login_time))



On Fri, Sep 24, 2010 at 4:32 PM, Travers Naran <tnaran@gmail.com> wrote:

> Hi all,
>
> Here's what I have. I have a list of log-in times for users and how
> long their sessions were.
>
> user, login_time, session_min
> alice, 2010/01/01 10:00, 145
> bob, 2010/01/01 11:00, 30
>
> What I want to do is create a bar chart showing, in 1/2 hour segments,
> the number of users logged in at the same time.  For example:
>
> 10:00 1
> 10:30 1
> 11:00 2
> 11:30 1
>
> The only way I can do this now is to send the data through a Perl
> script to generate raw data like:
>
> alice, 2010/01/01, 10:00
> alice, 2010/01/01, 10:30
> alice, 2010/01/01, 11:00
> ...
> bob, 2010/01/01, 11:00
>
> I've looked through the man pages for a couple hours now, and I can't
> find a better of way of doing this directly in R.  Any help or
> pointers?  Thanks in advance.
>
> ______________________________________________
> 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

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