I should add that if your V1 column is numeric, fiddling around with
?diff or equivalent will also identify the groupings for you and may
be faster than rle().
-- Bert
On Thu, Jan 24, 2013 at 3:32 PM, Bert Gunter <bgun...@gene.com> wrote:
> Your query is a little unclear to me, but I suspect
> ?rle
> is what you want.
>
> -- Bert
>
> On Thu, Jan 24, 2013 at 1:20 PM, Jeffrey Fuerte <fuert...@vcu.edu> wrote:
>> 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.
>>
>> [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help@r-project.org 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.
>
>
>
> --
>
> Bert Gunter
> Genentech Nonclinical Biostatistics
>
> Internal Contact Info:
> Phone: 467-7374
> Website:
> http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
--
Bert Gunter
Genentech Nonclinical Biostatistics
Internal Contact Info:
Phone: 467-7374
Website:
http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
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