Rolling sums for groups with uneven time gaps

Question

Here\'s the tweak to my previously posted question. Here\'s my data:

set.seed(3737)
DF2 = data.frame(user_id = c(rep(27, 7), rep(11, 7)),
            date = as.D         


        

Answer 1

logic : first group by user_id, followed by date. Now for each subset of data, we are checking which all dates lie between the current date and 7/14 days back using between() which returns a logical vector.

Based on this logical vector I add the value column

library(data.table)
setDT(DF2)[, `:=`(v_minus7 = sum(DF2$value[DF2$user_id == user_id][between(DF2$date[DF2$user_id == user_id], date-7, date, incbounds = TRUE)]), 
                 v_minus14 = sum(DF2$value[DF2$user_id == user_id][between(DF2$date[DF2$user_id == user_id], date-14, date, incbounds = TRUE)])),
           by = c("user_id", "date")][]
 #   user_id       date value v_minus7 v_minus14
 #1:      27 2016-01-01  15.0     15.0      15.0
 #2:      27 2016-01-03  22.4     37.4      37.4
 #3:      27 2016-01-05  13.3     50.7      50.7
 #4:      27 2016-01-07  21.9     72.6      72.6
 #5:      27 2016-01-10  20.6     78.2      93.2
 #6:      27 2016-01-14  18.6     61.1     111.8
 #7:      27 2016-01-16  16.4     55.6     113.2
 #8:      11 2016-01-01   6.8      6.8       6.8
 #9:      11 2016-01-03  21.3     28.1      28.1
#10:      11 2016-01-05  19.8     47.9      47.9
#11:      11 2016-01-07  22.0     69.9      69.9
#12:      11 2016-01-10  19.4     82.5      89.3
#13:      11 2016-01-14  17.5     58.9     106.8
#14:      11 2016-01-16  19.3     56.2     119.3

---

# from alexis_laz answer.
ff = function(date, value, minus){
  cs = cumsum(value)  
  i = findInterval(date - minus, date, rightmost.closed = TRUE) 
  w = which(as.logical(i))
  i[w] = cs[i[w]]
  cs - i
} 
setDT(DF2)
DF2[, `:=`( v_minus7 = ff(date, value, 7), 
            v_minus14 = ff(date, value, 14)), by = c("user_id")]