[R] means and variances of several groups in the matrix

[Jim Lemon]

kathie wrote:
> Dear R users, 
> 
> I have 32 observations in data x.  After sorting this, I want to compute
> means and variances of 3 groups divided by "nr".
> 
> Actually, the number of groups is flexible.  Any suggestion will be greatly
> appreciated. 
> 
Hi Kathryn,
One way (there are many others) is to use the brkdn function in the 
prettyR package. You have to create a grouping variable, but it's pretty 
easy...

group1<-rep(1:3,each=nr[1,])
group2<-rep(1:3,each=nr[2,])
y.df<-data.frame(y=y,group1=group1,group2=group2)
brkdn(y~group1,y.df,num.desc=c("mean","var"))
brkdn(y~group2,y.df,num.desc=c("mean","var"))

Jim