[R] sample (randomly select) from successive days

[Jim Lemon]

Hi Dagmar,
This will probably involve creating a variable to differentiate the
two days in each data.frame:

myframe$day<-as.Date(as.character(myframe$Timestamp),"%d.%m.%Y %H:%M:%S")
days<-unique(myframe$day)

Then just sample the two subsets and concatenate them:

myframe[c(sample(which(myframe$day==days[1]),2),
 sample(which(myframe$day==days[2]),2)),]

Jim


On Fri, Dec 7, 2018 at 8:08 PM Dagmar Cimiotti
<dagmar.cimiotti using ftz-west.uni-kiel.de> wrote:
>
> Dear all,
>
> I have data from a time span like this:
>
> myframe <- data.frame (Timestamp=c("24.09.2012 09:00:00", "24.09.2012 10:00:00","25.09.2012 09:00:00",
>                                     "25.09.2012 09:00:00","24.09.2012 09:00:00", "24.09.2012 10:00:00"),
>                          Event=c(50,60,30,40,42,54) )
> myframe
>
>
> I want to create a new dataframe which includes in this example the data from two successive days (in my real data I have a big time span and want data from 25 consecutive days). I understand that I can do a simple sample like this
>
> mysample <- myframe[sample(1:nrow(myframe), 4,replace=FALSE),]
> mysample
>
> But I need the data from consecutive days in my random sample. Can anyone help me with this?
>
>
> Many thanks in advance,
> Dagmar
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.