Create unique ID based on repeated IDs

Question

I received some data from a colleague who is working with animal observations recorded in several transects. However my colleague used the same three ID codes for identifying each transect: 1, 7, 13 and 19. I would like to replace the repeated IDs with unique IDs. This image shows what I want to do:

Here's the corresponding code:

example_data<-structure(list(ID_Transect = c(1L, 1L, 1L, 1L, 1L, 1L, 7L, 7L, 
                                             7L, 7L, 7L, 7L, 13L, 13L, 13L, 13L, 13L, 13L, 19L, 19L, 19L, 
                                             19L, 19L, 19L, 1L, 1L, 1L, 1L, 1L, 1L, 7L, 7L, 7L, 7L, 7L, 7L), 
                             transect_id = c(1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 
                   2L, 3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 4L, 5L, 5L, 5L, 
                   5L, 5L, 5L, 6L, 6L, 6L, 6L, 6L, 6L)), class = "data.frame", row.names = c(NA, 
                                                                                             -36L))

score 3 · Answer 1 · answered Jun 18 '21 at 16:48

3

We can also do

library(data.table)
setDT(example_data)[, transect_id := rleid(ID_Transect)]

answered Jun 18 '21 at 16:48

akrun

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score 2 · Accepted Answer · answered Jun 18 '21 at 10:25

You can use data.table rleid -

example_data$transect_id <- data.table::rleid(example_data$ID_Transect)
#[1] 1 1 1 1 1 1 2 2 2 2 2 2 3 3 3 3 3 3 4 4 4 4 4 4 5 5 5 5 5 5 6 6 6 6 6 6

In base R we can use rle -

with(rle(example_data$ID_Transect), rep(seq_along(values), lengths))

Or diff + cumsum -

cumsum(c(TRUE, diff(example_data$ID_Transect) != 0))

Create unique ID based on repeated IDs

2 Answers2