R: matrix to indexes

Question

I have a matrix like

      [,1] [,2]
 [1,]    1    3
 [2,]    4    6
 [3,]   11   12
 [4,]   13   14

I want to convert this matrix to a vector

Answer 1

Here's an answer using IRanges package:

require(IRanges)
xx.ir <- IRanges(start = xx[,1], end = xx[,2])
as.vector(coverage(xx.ir))
# [1] 1 1 1 1 1 1 0 0 0 0 1 1 1 1

If you specify a min and max value of your entire vector length, then:

max.val <- 20
min.val <- 1
c(rep(0, min.val-1), as.vector(coverage(xx.ir)), rep(0, max.val-max(xx)))