[R] loop with date

[arun]

HI,
If you want to do daily mean, sum etc.
you could try ?tapply(), ?ave(), ?aggregate(), ?ddply() etc.
For e.g.
 ave(myframe2$Speed,as.Date(myframe2$myframestime),FUN=sum)
#[1]  4  4  4 12 12 12
tapply(myframe2$Speed,as.Date(myframe2$myframestime),FUN=mean)
#2012-09-24 2012-09-25 
 # 1.333333   4.000000 

It is better to show the complex data as an example using dput()
A.K.




----- Original Message -----
From: Tagmarie <Ramgad82 at gmx.net>
To: r-help at r-project.org
Cc: 
Sent: Tuesday, November 27, 2012 9:02 AM
Subject: [R] loop with date

Hello, 
I tried to construct my very first loop today and completly failed :-(
Maybe someone can help me? 
I have a dataframe somewhat like this one: 

myframe <- data.frame (Timestamp=c("24.09.2012 09:00", "24.09.2012 10:00",
"24.09.2012 11:00", 
                                   "25.09.2012 09:00", "25.09.2012 10:00",
"25.09.2012 11:00"), 
                        Speed=c(1,1,2,5,1,6))                                  
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 construct a loop for every day, i.e. for each day I want to do
some calculations. 
(I know in the example it would be easier to do it differently, my real data
are little more complex). 

And BTW: Thanks for helping me earlier today with that other problem :-) 




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