R help - Oct 2012 - mean of a value of the last 2 hours using plyr (Thank you)

Hi dear three helpers,

Thanks a lot! Your solutions worked great. Again I learned a lot.

Tagmarie

Am 25.10.2012 18:36, schrieb Felipe Carrillo:
> Another option using plyr,
> library(plyr)
> myframe <- data.frame (ID=c("Ernie", "Ernie",
"Ernie", "Bert", "Bert",
> "Bert"), Timestamp=c("24.09.2012 09:00",
"24.09.2012 10:00", "24.09.2012
> 11:00"), Hunger=c(1,1,1,2,2,1) )
> myframe
> myframestime <- as.POSIXct (strptime(as.character(myframe$Timestamp),
> "%d.%m.%Y %H:%M"), tz="GMT")
> myframestime
> myframe2 <- cbind (myframe,myframestime)
> myframe2
> ddply(myframe2,.(ID),summarise,Last2=mean(tail(Hunger,2)))
> Felipe D. Carrillo
> Supervisory Fishery Biologist
> Department of the Interior
> US Fish & Wildlife Service
> California, USA
> http://www.fws.gov/redbluff/rbdd_jsmp.aspx
>
>     *From:* Tagmarie <Ramgad82@gmx.net>
>     *To:* r-help@r-project.org
>     *Sent:* Thursday, October 25, 2012 7:35 AM
>     *Subject:* [R] mean of a value of the last 2 hours
>
>     Hello,
>     I have a data frame somewhat like that:
>
>     myframe <- data.frame (ID=c("Ernie", "Ernie",
"Ernie", "Bert", "Bert",
>     "Bert"), Timestamp=c("24.09.2012 09:00",
"24.09.2012 10:00",
>     "24.09.2012
>     11:00"), Hunger=c(1,1,1,2,2,1) )
>     myframestime <- as.POSIXct
(strptime(as.character(myframe$Timestamp),
>     "%d.%m.%Y %H:%M"), tz="GMT")
>     myframe2 <- cbind (myframe,myframestime)
>     myframe2$Timestamp <- NULL
>     myframe2
>
>     I want to add an additional column at the right and get in each
>     row a value
>     which shows the mean of "hunger" of the last two hours.
>
>     Does anyone know how that works? That would be very helpful.
>
>
>
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>    
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>
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>




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