Reset cumsum to zero in R

Question

I have a problem. For example, I have this:

id truth count 1 1 1 2 1 2 3 0 0 4 1 1 5 1 2 6 1 3 8 0 0

I tried this:

 fun <- rle(df$truth) df$count <- unlist(sapply(fun$lengths, function(x) {return(1:x)}))

But it does not work.

+3

Johnny P. Feb 05 '14 at 15:32

1 answer

Sven hohenstein · Accepted Answer · 2014-02-05T15:48:24+0000

Here is the approach. Based on ave :

 transform(dat, count = truth * ave(truth, c(0L, cumsum(diff(truth) != 0)), FUN = seq_along))

where dat is the name of your data frame.