R/dplyr Get running maximum value

Question

I have below data

CODE	TIME	VALUE
ABC	1	40
ABC	2	50
ABC	3	30
ABC	4	60

I am trying to find the maximum VALUE until a given timepoint. For example, for TIME == 2 and TIME == 3, MAXVALUE should be 50.

For TIME == 4 MAXVALUE should be 60.

I trying to get below table,

CODE	TIME	VALUE	MAXVALUE
ABC	1	40	40
ABC	2	50	50
ABC	3	30	50
ABC	4	60	60

Please suggest how can I do in R using dplyr

Answer 1

you can simply use cummax:

library(dplyr)
df %>%
  arrange(time) %>%
  mutate(maxvalue = cummax(value))