Compute rolling sum by id variables, with missing timepoints

Question

I\'m trying to learn R and there are a few things I\'ve done for 10+ years in SAS that I cannot quite figure out the best way to do in R. Take this data:

 id         


        

Answer 1

With runner package one can calculate everything on rolling windows. Below example of using sum_run

library(runner)
df %>%
  group_by(id) %>%
  mutate(
    output = sum_run(count, k = 30*4, idx = t)   
  )

#             
#     1 A     2010-01-15     1       1      1
#     1 A     2010-02-15     2       3      3
#     1 B     2010-04-15     3       3      6
#     1 B     2010-09-15     4       4      4
#     2 A     2010-01-15     5       5      5
#     2 B     2010-06-15     6       6      6
#     2 B     2010-08-15     7      13     13
#     2 B     2010-09-15     8      21     21