Rolf's solution works for the situation where all duplicated values
are contiguous, which may be what you need. However, I wondered how it
could be done if this were not the case. Below is an answer. It is not
as efficient or elegant as Rolf's solution for the contiguous case I
think; maybe someone will come up with something better. But I think
it works. Here's an example with code:
> w <- c(1:5,3,1,2,7,8,5,5,5,2,3)
> w
[1] 1 2 3 4 5 3 1 2 7 8 5 5 5 2 3
> d <- 0+duplicated(w)
> for(x in unique(w)){
+ i <- w==x
+ d[i]<-1+ cumsum(d[i])
+
+ }
> d
[1] 1 1 1 1 1 2 2 2 1 1 2 3 4 3 3
As always, corrections and/or improvements welcome.
Cheers,
Bert
Bert Gunter
"Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom."
-- Clifford Stoll
On Sat, Oct 24, 2015 at 4:02 PM, Rolf Turner <r.tur...@auckland.ac.nz> wrote:
> On 25/10/15 11:28, John Sorkin wrote:
>>
>> I have a file that has (1) Line numbers, (2) IDs. A given ID number can
>> appear in more than one row. For each row with a repeated ID, I want to add
>> a number that gives the sequence number of the repeated ID number. The R
>> code below demonstrates what I want to have, without any attempt to produce
>> the result, as I have no idea how to accomplish my goal.
>>
>>
>> line <- c(1,2,3,4,5,6,7,8,9,10)
>> ID<- c(1,1,2,3,4,5,6,7,8,8)
>> cat("Note lines 1 and 2 both contain ID 1; lines 9 and 10 both contain ID
>> 8")
>> cbind(line,ID)
>> Seq <- c(1,2,1,1,1,1,1,1,1,2)
>> cat("Sequence numbers within ID added to the data")
>> cbind(line,ID,Seq)
>
>
> I *think* that
>
> unlist(lapply(rle(ID)$lengths,seq_len))
>
> gives what you want. At least it does for the given example.
>
> cheers,
>
> Rolf Turner
>
> --
> Technical Editor ANZJS
> Department of Statistics
> University of Auckland
> Phone: +64-9-373-7599 ext. 88276
>
>
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