[R] subset a data.frame

[Simone Gabbriellini]

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
>