Summations by conditions on another row dealing with time - r

Question

I am looking to run a cumulative sum at every row for values that occur in two columns before and after that point. So in this case I have volume of 2 incident types at every given minute over two days. I want to create a column which adds all the incidents that occured before and after for each row by the type. Sumif from excel comes to mind but I'm not sure how to port that over to R:
EDIT: ADDED set.seed and easier numbers
I have the following data set:
set.seed(42)
master_min =
setDT(
data.frame(master_min = seq(
from=as.POSIXct("2016-1-1 0:00", tz="America/New_York"),
to=as.POSIXct("2016-1-2 23:00", tz="America/New_York"),
by="min"
))
)
incident1= round(runif(2821, min=0, max=10))
incident2= round(runif(2821, min=0, max=10))
master_min = head(cbind(master_min, incident1, incident2), 5)
How do I essentially compute the following logic:
for each row, sum all the incident1s that occured before that row's timestamp and all the incident2s that occured after that row's timestamp? It would be great to get a data table solution, if not a dplyr as I am working with a large dataset. Below is a before and after for the data`:
BEFORE:
master_min incident1 incident2
1: 2016-01-01 00:00:00 9 6
2: 2016-01-01 00:01:00 9 5
3: 2016-01-01 00:02:00 3 5
4: 2016-01-01 00:03:00 8 6
5: 2016-01-01 00:04:00 6 9
AFTER THE CALCULATION:
master_min incident1 incident2 new_column
1: 2016-01-01 00:00:00 9 6 25
2: 2016-01-01 00:01:00 9 5 29
3: 2016-01-01 00:02:00 3 5 33
4: 2016-01-01 00:03:00 8 6 30
5: 2016-01-01 00:04:00 6 9 29

Answer 1

If I understand correctly:
# Cumsum of incident1, without current row:
master_min$sum1 <- cumsum(master_min$incident1) - master_min$incident1
# Reverse cumsum of incident2, without current row:
master_min$sum2 <- rev(cumsum(rev(master_min$incident2))) - master_min$incident2
# Your new column:
master_min$new_column <- master_min$sum1 + master_min$sum2

Answer 2

*update
The following two lines can do the job
master_min$sum1 <- cumsum(master_min$incident1)
master_min$sum2 <- sum(master_min$incident2) - cumsum(master_min$incident2)
I rewrote the question a bit to show a bit more comprehensive structure
library(data.table)
master_min <-
setDT(
data.frame(master_min = seq(
from=as.POSIXct("2016-1-1 0:00", tz="America/New_York"),
to=as.POSIXct("2016-1-1 0:09", tz="America/New_York"),
by="min"
))
)
set.seed(2)
incident1= as.integer(runif(10, min=0, max=10))
incident2= as.integer(runif(10, min=0, max=10))
master_min = cbind(master_min, incident1, incident2)
Now master_min looks like this
> master_min
master_min incident1 incident2
1: 2016-01-01 00:00:00 1 5
2: 2016-01-01 00:01:00 7 2
3: 2016-01-01 00:02:00 5 7
4: 2016-01-01 00:03:00 1 1
5: 2016-01-01 00:04:00 9 4
6: 2016-01-01 00:05:00 9 8
7: 2016-01-01 00:06:00 1 9
8: 2016-01-01 00:07:00 8 2
9: 2016-01-01 00:08:00 4 4
10: 2016-01-01 00:09:00 5 0
Apply transformations
master_min$sum1 <- cumsum(master_min$incident1)
master_min$sum2 <- sum(master_min$incident2) - cumsum(master_min$incident2)
Results
> master_min
master_min incident1 incident2 sum1 sum2
1: 2016-01-01 00:00:00 1 5 1 37
2: 2016-01-01 00:01:00 7 2 8 35
3: 2016-01-01 00:02:00 5 7 13 28
4: 2016-01-01 00:03:00 1 1 14 27
5: 2016-01-01 00:04:00 9 4 23 23
6: 2016-01-01 00:05:00 9 8 32 15
7: 2016-01-01 00:06:00 1 9 33 6
8: 2016-01-01 00:07:00 8 2 41 4
9: 2016-01-01 00:08:00 4 4 45 0
10: 2016-01-01 00:09:00 5 0 50 0