Remove duplicate events within delta time - r

Question

Given the datraframe below
class timestamp
1 A 2019-02-14 15:00:29
2 A 2019-01-27 17:59:53
3 A 2019-01-27 18:00:00
4 B 2019-02-02 18:00:00
5 C 2019-03-08 16:00:37
observation 2 and 3 point to the same event. How do I remove rows belonging to the same class if another timestamp within 2 minutes already exists?
Desired output:
class timestamp
1 A 2019-02-14 15:00:00
2 B 2019-01-27 18:00:00
3 A 2019-02-02 18:00:00
4 C 2019-03-08 16:00:00
round( ,c("mins")) can be used to get rid of the second component but if the timestamps are to far off some test samples will be rounded to the wrong minute leaving still different timestamps

Answer 1

EDIT
I think I over-complicated the problem in first attempt, I think what would work for your case is to round time for 2 minute intervals which we can do using round_date from lubridate .
library(lubridate)
library(dplyr)
df %>%
mutate(timestamp = round_date(as.POSIXct(timestamp), unit = "2 minutes")) %>%
group_by(class) %>%
filter(!duplicated(timestamp))
# class timestamp
# <chr> <dttm>
#1 A 2019-02-14 15:00:00
#2 A 2019-01-27 18:00:00
#3 B 2019-02-02 18:00:00
#4 C 2019-03-08 16:00:00
Original Attempt
We can first convert the timestamp to POSIXct object, then arrange rows by class and timestamp, use cut to divide them into "2 min" interval and then remove duplicates.
library(dplyr)
df %>%
mutate(timestamp = as.POSIXct(timestamp)) %>%
arrange(class, timestamp) %>%
group_by(class) %>%
filter(!duplicated(as.numeric(cut(timestamp, breaks = "2 mins")), fromLast = TRUE))
# class timestamp
# <chr> <dttm>
#1 A 2019-01-27 18:00:00
#2 A 2019-02-14 15:00:29
#3 B 2019-02-02 18:00:00
#4 C 2019-03-08 16:00:37
Here, I haven't changed or rounded the timestamp column and kept it as it is but it would be simple to round it if you use cut in mutate. Also if you want to keep the first entry like 2019-01-27 17:59:53 then remove fromLast = TRUE argument.