CODEWITHSUNDEEP
r
user3242725
user3242725

Reputation: 21

counting numbers between two zeros

Suppose I have a vector, say:

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

and I would like to obtain a vector that sums the values that falls between two zeros, i.e. the output should look like:

y = c(1,2,4,1,1,1)

Note that all ones should have zero at the beginning and zero at the end, otherwise it will not be counted. so the string 01010 only produce 1.

I tried to use run length with an index of zeros.

Thanks in Advance

Upvotes: 0

Views: 148

Answers (1)

flodel
flodel

Reputation: 89067

sum.between.zeroes <- function(x) {
  library(stringr)
  x.str <- paste(x, collapse = "")
  nchar(str_extract_all(x.str, "01+0")[[1]]) - 2L
}

sum.between.zeroes(c(1,0,1,0,0,0,1,1,0,0,1,1,1,1,0,1,1,0,1,0,0,0,0,0,1,0,1,0,1,0))
# [1] 1 2 4 1 1 1

sum.between.zeroes(c(0,1,0,1,0))
# [1] 1

sum.between.zeroes(c(1,1))
# integer(0)

If you want to remain within the base package, you can use gregexpr and regmatches:

sum.between.zeroes <- function(x) {
  x.str <- paste(x, collapse = "")
  nchar(regmatches(x.str, gregexpr("01+0", x.str))[[1]]) - 2L
}

Upvotes: 5

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