rdataframedplyrtidyversesequential

How to create sequence of integers in R?

I've got dataframe like so:

id    year
001   1988
001   1988
001   1988
001   1988
001   1988
002   1972
002   1972
002   1972
002   1972

For each id, I would like to convert the variable year into a sequence beginning from the first observation, increasing by one in each consecutive row. The desired output:

id    year
001   1988
001   1989
001   1990
001   1991
001   1992
002   1972
002   1973
002   1974
002   1975

How do I do this? A tidyverse solution would be preferred. Thanks.

My data:

df <- data.frame(id = c("001", "001", "001", "001", "001", "002", "002", "002", "002"),
                 year = c(1988, 1988, 1988, 1988, 1988, 1972, 1972, 1972, 1972))
Solution

  • With seq:

    library(dplyr)
df %>% 
  mutate(year = seq(first(year), length.out = n()), .by = id)

#   id year
# 1  1 1988
# 2  1 1989
# 3  1 1990
# 4  1 1991
# 5  1 1992
# 6  2 1972
# 7  2 1973
# 8  2 1974
# 9  2 1975