[R] Group level frequencies

[Dimitris Rizopoulos]

well, I'm not completely sure I understand what you want to compute 
but you may try the following:

data.ml <- data.frame(i = 1:8, g = factor(c(1,1,1,2,2,3,3,3)),
    var1 = c(3,3,3,4,4,4,4,4), var2 = c(8,8,8,2,2,4,4,4))
################
data.ml[!duplicated(data.ml$g), -1]
# or
t(sapply(split(data.ml[c("var1", "var2")], data.ml$g),
    colMeans))


I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Kunzler, Andreas" <a.kunzler at bzaek.de>
To: <r-help at r-project.org>
Sent: Wednesday, July 16, 2008 10:21 AM
Subject: [R] Group level frequencies


> Dear List,
>
> I have Multi-level Data
>
> i= Indivitual Level
> g= Group Level
> var1= First Variable of interest
> var2= Second Variable of interest
>
> and I want to count the frequency of "var1" and "var2" on the group
> level.
>
> I found a way, but there must be a much simpler way.
>
> data.ml <-
> data.frame(i=c(1:8),g=as.factor(c(1,1,1,2,2,3,3,3)),var1=c(3,3,3,4,4,4,4
> ,4), var2=c(8,8,8,2,2,4,4,4))
>
> therefore the data looks like
>  i g var1 var2
> 1 1 1    3    8
> 2 2 1    3    8
> 3 3 1    3    8
> 4 4 2    4    2
> 5 5 2    4    2
> 6 6 3    4    4
> 7 7 3    4    4
> 8 8 3    4    4
>
> 1. I used tapply to get the (Group)mean of var1 and var2 in separate
> Equations. The result will be two one-dimensional Array with 
> rownames.
> 2. I Transformed the Arrays in two data.frames
> 3. I merged the data.frames
>
> d.var1 <-
> data.frame(id=rownames(tapply(data.ml$var1,data.ml$g,mean)),var1=as.nume
> ric(tapply(data.ml$var1,data.ml$g,mean)))
>
> d.var2 <-
> data.frame(id=rownames(tapply(data.ml$var2,data.ml$g,mean)),var2=as.nume
> ric(tapply(data.ml$var2,data.ml$g,mean)))
>
> data.gl <- d.var1
> data.gl$var2 <- d.var2$var2
>
> By putting the data.frames d.var1 and d.var2 together in a new
> data.frame data.gl I would like to take control of the "id"-factor
>
> There must be an easier way.
>
> Thank you.
>
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> 


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