Hi,
Try this:
#changed data to dat1
list1<-split(dat1,list(dat1$dim1,dat1$dim2,dat1$dim3))
names(list1)<-1:length(list1)
res<-do.call(rbind,lapply(list1,function(x)
data.frame(x,group=names(list1)[match.call()[[2]][[3]]])))
row.names(res)<-1:nrow(res)
head(res)
# var dim1 dim2 dim3 group
#1 0.06896418 x 1 1 1
#2 0.44958942 x 1 1 1
#3 0.08163725 y 1 1 2
#4 0.21945238 y 1 1 2
#5 0.05695142 z 1 1 3
#6 0.36656387 x 2 1 4
A.K.
----- Original Message -----
From: Francesco Sarracino <f.sarrac...@gmail.com>
To: r-help@r-project.org
Cc:
Sent: Monday, December 10, 2012 9:33 AM
Subject: [R] equivalent of group command of the egen function in Stata
Dear R listers,
I am trying to create a new variable that uniquely identifies groups of
observations in a dataset. So far I couldn't figure out how to do this in
R. In Stata I would simply type:
egen newvar = group(dim1, dim2, dim3)
Please, find below a quick example to show what I am dealing with:
I have a dataset with 4 variables:
var <- runif(50) ## a variable that I want to group
dim1 <- factor(rep(1:3, length.out= 50), labels = c("x","y","z") ) ## 3
variables that should form the groups
dim2 <- rep(1:2, length.out= 50)
dim3 <- rep(1:5, length.out= 50)
data <- data.frame(var, dim1, dim2, dim3)
I am trying to build a fifth one (let's say: group_id) to uniquely identify
groups of observations as defined by dim1, dim2 and dim3, i.e. 30 groups.
can you please help me figuring out how to do it?
thanks in advance,
f.
--
Francesco Sarracino, Ph.D.
https://sites.google.com/site/fsarracino/
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