CODEWITHSUNDEEP
rdplyr
DA_PA
DA_PA

Reputation: 231

Assign group id start from 0 and end with 1 in R

I have a dataset the following

DT <- data.drame(v1 = c(0,0,0,1,0,0,1))

I want to create a ID cumulatively stopped at a value of 1.

The ID should be 

ID<-c(1,2,3,4,1,2,3)

Upvotes: 0

Views: 112

Answers (2)

Nikhil Gupta
Nikhil Gupta

Reputation: 1486

If you are using dplyr, this will do the trick.

DT = data.frame(v1 = c(0,0,0,1,0,0,1))

DT %>% 
  dplyr::mutate(rno = row_number()) %>% 
  dplyr::mutate(group = ifelse(v1 == 0, NA, rno)) %>% 
  tidyr::fill(group, .direction = "up") %>% 
  dplyr::group_by(group) %>% 
  dplyr::mutate(ID = row_number()) %>% 
  dplyr::ungroup() %>% 
  dplyr::select(v1, ID)

Upvotes: 1

Ronak Shah
Ronak Shah

Reputation: 388982

In base R, we can use ave : 

with(DT, ave(v1, c(0, cumsum(v1)[-length(v1)]), FUN = seq_along))
#[1] 1 2 3 4 1 2 3

In dplyr , we can use lag to create groups and assign row number in each group. 

library(dplyr)
DT %>% group_by(gr = lag(cumsum(v1), default = 0)) %>% mutate(ID = row_number())

and we can use the same logic in data.table : 

library(data.table)
setDT(DT)[, ID := seq_len(.N), shift(cumsum(v1), fill = 0)]

Upvotes: 0

Related Questions