Hi:

Here's another way:

c1<-c(1,2,3,2,2,3,1,2,2,2)

c2<-c(5,6,7,7,5,7,5,7,6,6)

c3<-rnorm(10)

x <- data.frame(c1 = factor(c1), c2 = factor(c2), c3)

x <- transform(x, mean = ave(c3, c1, c2, FUN = mean))

Yet another with function ddply() in package plyr:

ddply(x, .(c1, c2), transform, mean = mean(c3))

HTH,

Dennis

On Fri, Feb 25, 2011 at 7:14 AM, zem <

[hidden email]> wrote:

>

> Yeah, you are right

> i want to post an short example what i want to do .. and in the meantime i

> solved the problem ...

> but here is:

> i have something like this dataframe:

> c1<-c(1,2,3,2,2,3,1,2,2,2)

> c2<-c(5,6,7,7,5,7,5,7,6,6)

> c3<-rnorm(10)

> x<-cbind(c1,c2,c3)

> > x

> c1 c2 c3

> [1,] 1 5 0.08279036

> [2,] 2 6 0.59135988

> [3,] 3 7 1.45520468

> [4,] 2 7 -1.70094640

> [5,] 2 5 0.13065228

> [6,] 3 7 -1.12080980

> [7,] 1 5 0.42779354

> [8,] 2 7 -1.53111972

> [9,] 2 6 0.29299987

> [10,] 2 6 -0.01602095

>

> #whith aggregate i receive this:

> >aggregate(x[,3],list(x[,1],x[,2]),mean)

> Group.1 Group.2 x

> 1 1 5 0.2552920

> 2 2 5 0.1306523

> 3 2 6 0.2894463

> 4 2 7 -1.6160331

> 5 3 7 0.1671974

>

>

> and the problem was that i was grouping by 2 columns, so i couldn't copy

> the

> result to x.

>

> the solution was i made another column with paste(x[,1],x[,2],sep="_")

> and then i used the solution from this link:

>

http://tolstoy.newcastle.edu.au/R/help/06/07/30184.html> so i solved my problem

>

> Ivan, many thanks for your support and quik responses! :)

>

> --

> View this message in context:

>

http://r.789695.n4.nabble.com/group-by-in-data-frame-tp3324240p3324608.html> Sent from the R help mailing list archive at Nabble.com.

>

> ______________________________________________

>

[hidden email] mailing list

>

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.

>

[[alternative HTML version deleted]]

______________________________________________

[hidden email] mailing list

https://stat.ethz.ch/mailman/listinfo/r-helpPLEASE do read the posting guide

http://www.R-project.org/posting-guide.htmland provide commented, minimal, self-contained, reproducible code.