How to create id variable by grouping sequenced numbers?

Question

I want to add ID variable in this data. If receipt_ids are sequenced numbers, then those have same IDs.

CUST_NO_ID  receipt_id      dollar
  12         29               


        

Answer 1

We can use data.table

library(data.table)
setDT(df)[, id := cumsum(c(TRUE, diff(receipt_id)!=1))]

Or use the shift

setDT(df)[, id := cumsum((receipt_id - shift(receipt_id, fill=receipt_id[1]))!=1)]