Hi, 

I have to create some GRanges objects, which are located on the + and - strand (The features represent regions on transcripts.). Here a reproducible example: 

GRanges(seqnames = Rle(c("chr1", "chr2", "chr3", "chr4")), 
        ranges = IRanges(10:13, width=3),
        strand = Rle(c("+", "-", "+", "-")))

However, IRanges works strand independent, meaning that 10+3, 11+3... but on the "-" strand, the start should be 8 and the end 11. I looked at the vignette, but did not find any information. I know there are workarounds, but I wondered if this might be somewhere implemented? 

I want: 

seqnames    ranges strand
         <Rle> <IRanges>  <Rle>
  [1]     chr1  [10, 12]      +
  [2]     chr2  [9, 11]      -
  [3]     chr3  [12, 14]      +
  [4]     chr4  [11, 13]      -

The resize() method on GRanges is strand aware, so you could do:

gr <- GRanges(seqnames = Rle(c("chr1", "chr2", "chr3", "chr4")), 
              ranges = IRanges(10:13, width=1L),
              strand = Rle(c("+", "-", "+", "-")))
resize(gr, 3L)