How to obtain a position of last non-zero element

Question

I've got a binary variable representing if event happened or not:

event <- c(0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0)

I need to obtain a variable that would indicate the time when the last event happened. The expected output would be:

last_event <- c(0, 0, 0, 0, 5, 5, 5, 5, 5, 5, 5, 5, 13, 13, 13, 13)

How can I obtain that with base R, tidyverse or any other way?

Answer 1

利用您具有二进制向量的事实，以下给出了所需的输出：

cummax(seq_along(event) * event)

Answer 2

每当您需要用值填充重复项时，请考虑游程编码。

在这种情况下，您可以确定行程长度，然后count == 0根据次数重复索引：

lengths = rle(event == 0)$lengths
nonzeros = which(event != 0)
runs = c(0, rep(nonzeros, each = 2))
result = rep(runs, lengths)

或者，将运行替换为RLE，然后将其求逆：

rle = rle(event == 0)
nonzeros = which(event != 0)
rle$values = c(0, rep(nonzeros, each = 2))
result = inverse.rle(rle)