Hello,
I'm not sure how to explain what I'm looking for but essentially I have a
test dataset that looks like this:
test:
V1
1 1
2 1
3 1
4 2
5 2
6 2
7 1
8 1
9 1
10 2
11 2
12 2
And what I want to be able to do is create another column that captures a
"grouping" variable that looks like this:
test
V1 group
1 1 1
2 1 1
3 1 1
4 2 2
5 2 2
6 2 2
7 1 3
8 1 3
9 1 3
10 2 4
11 2 4
12 2 4
So, it's keeping track of the changes in V1, but even though V1 could be
the same in different instances, the group is treating it as a new group.
I have written a loop that does what I want, but this takes too long to
run, so I was hoping for either a faster approach or an ifelse statement.
Any ideas?
By the loop I was using looks like this:
groupings <- 1
test$group[1] <- groupings
for (i in 2:length(test$V1))
{
if (test$V1[i]==test$V1[i-1])
{
test$group[i] <- groupings
} else {
groupings <- groupings+1
test$group[i] <- groupings
}
}
Thanks for the help.
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