[R] how to create duplicated ID in multi-records per subject dataset

[andrew]

if the records are in the file dupIDs.txt, then when you read them in,
the IDs become factors.  Coercing them to numeric gets them to assign
a unique number to each factor.

So, you could try the following:

dupIDs <- read.table("dupIDs.txt", header = T)
dupIDs$ID2 <- cummax(as.numeric(dupIDs$ID)-1)

> dupIDs
  ID record ID2
1  1     20   1
2  .     30   1
3  .     25   1
4  2     26   2
5  .     15   2
6  3     21   3

HTH,

Andrew.


On Dec 15, 12:56 pm, "Zhixin Liu" <z... at efs.mq.edu.au> wrote:
> Hi R helpers,
>
> If I have a dataset looks like:
> ID   record
> 1        20
> .         30
> .         25
> 2         26
> .         15
> 3         21
> 4.....................
>
> And I want it becomes
> ID   record
> 1        20
> 1        30
> 1        25
> 2         26
> 2        15
> 3         21
> 4.....................
>
> That is, I have to duplicate IDs for those with multiple records. I am wondering it is possible to be done in R, and I am grateful if you would like to show me the direction.
>
> Many thanks!
>
> Zhixin
>
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