R: calculate the number of occurrences of a specific event in a specified time future

Question

my simplified data looks like this:

set.seed(1453); x = sample(0:1, 10, TRUE)
date = c('2016-01-01', '2016-01-05', '2016-01-07',  '2016-01-12',  '2016-01-16',  '2016-01-20',
             '2016-01-20',  '2016-01-25',  '2016-01-26',  '2016-01-31')


df = data.frame(x, date = as.Date(date))


df 
x       date
1 2016-01-01
0 2016-01-05
1 2016-01-07
0 2016-01-12
0 2016-01-16
1 2016-01-20
1 2016-01-20
0 2016-01-25
0 2016-01-26
1 2016-01-31

I'd like to calculate the number of occurrences for x == 1 within a specified time period, e.g. 14 and 30 days from the current date (but excluding the current entry, if it is x == 1. The desired output would look like this:

solution
x       date x_plus14 x_plus30
1 2016-01-01        1        3
0 2016-01-05        1        4
1 2016-01-07        2        3
0 2016-01-12        2        3
0 2016-01-16        2        3
1 2016-01-20        2        2
1 2016-01-20        1        1
0 2016-01-25        1        1
0 2016-01-26        1        1
1 2016-01-31        0        0

Ideally, I'd like this to be in dplyr, but it is not a must. Any ideas how to achieve this? Thanks a lot for your help!

Answer 1

Adding another approach based on findInterval:

cs = cumsum(df$x) # cumulative number of occurences
data.frame(df, 
           plus14 = cs[findInterval(df$date + 14, df$date, left.open = TRUE)] - cs, 
           plus30 = cs[findInterval(df$date + 30, df$date, left.open = TRUE)] - cs)
#   x       date plus14 plus30
#1  1 2016-01-01      1      3
#2  0 2016-01-05      1      4
#3  1 2016-01-07      2      3
#4  0 2016-01-12      2      3
#5  0 2016-01-16      2      3
#6  1 2016-01-20      2      2
#7  1 2016-01-20      1      1
#8  0 2016-01-25      1      1
#9  0 2016-01-26      1      1
#10 1 2016-01-31      0      0