Cumulative sum that resets when 0 is encountered

Question

I would like to do a cumulative sum on a field but reset the aggregated value whenever a 0 is encountered.

Here is an example of what I want :

data.f         


        

Answer 1

Another late idea:

ff = function(x)
{
    cs = cumsum(x)
    cs - cummax((x == 0) * cs)
}
ff(c(0, 1, 3, 0, 0, 5, 2))
#[1] 0 1 4 0 0 5 7

And to compare:

library(data.table)
ffdt = function(x) 
    data.table(x)[, whatiwant := cumsum(x), by = rleid(x == 0L)]$whatiwant

x = as.numeric(x) ##because 'cumsum' causes integer overflow
identical(ff(x), ffdt(x))
#[1] TRUE
microbenchmark::microbenchmark(ff(x), ffdt(x), times = 25)
#Unit: milliseconds
#    expr      min       lq   median       uq      max neval
#   ff(x) 315.8010 362.1089 372.1273 386.3892 405.5218    25
# ffdt(x) 374.6315 407.2754 417.6675 447.8305 534.8153    25