many thanks, works perfectly!
best,
Simone
Il giorno 02/nov/2010, alle ore 17.17, David Winsemius ha scritto:
>
> On Nov 2, 2010, at 11:53 AM, Simone Gabbriellini wrote:
>
>> Hello List,
>>
>> this should be simple, but cannot figure it out. I am trying to subset a
>> data.frame like this:
>>
>>> data4
>> users time
>> 1 user5 2009-12-01 14:09:58
>> 2 user1 2009-12-01 14:40:16
>> 3 user8 2009-12-04 08:18:37
>> 4 user6 2009-12-04 08:18:37
>> 5 user83 2009-12-04 08:18:37
>> 6 user82 2009-12-04 08:18:37
>> 7 user31 2009-12-04 08:18:37
>> 8 user85 2009-12-04 08:18:37
>> 9 user33 2009-12-04 08:18:37
>> 10 user2 2010-01-05 07:18:36
>>
>> I would like to subset it and retain, let's say, only the data with time <
>> '2010-01-05 07:18:36', but I have no idea about the sintax to do that.
>>
>> is something like this close to the correct way:
>>
>> active<-data4['time'<= as.POSIXct("2010-01-05 07:18:36", origin="1970-01-01
>> 00:00:00-00")]
>
> Close. Try:
>
> active <- data4[data4$time <= as.POSIXct("2010-01-05 07:18:36",
> origin="1970-01-01 00:00:00-00") , ]
>
> Or:
>
> active <- subset(data4, time <= as.POSIXct("2010-01-05 07:18:36",
> origin="1970-01-01 00:00:00-00") )
>
>>
>
>
> --
>
> David Winsemius, MD
> West Hartford, CT
>
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