Find the difference in Data based on ID in R

Question

I would like to find out the difference in days between the two date field based on the ID number. And the last date found based on ID would be 0 (Date - itself) Example a tibble dataframe:

ID	Date	Difference
1	1/1/2022	2
1	3/1/2022	0
2	2/1/2022	3
2	5/1/2022	23
2	28/1/2022	0

Is there any way to achieve this?

Answer 1

You could use diff() to calculate lagged differences.

library(dplyr)

df %>%
  group_by(ID) %>%
  mutate(Date = as.Date(Date, '%d/%m/%Y'),
         Difference = c(diff(Date), 0)) %>%
  ungroup()

# # A tibble: 5 × 3
#      ID Date       Difference
#   <int> <date>     <drtn>
# 1     1 2022-01-01  2 days
# 2     1 2022-01-03  0 days
# 3     2 2022-01-02  3 days
# 4     2 2022-01-05 23 days
# 5     2 2022-01-28  0 days