Hey,

I'm trying to save several GRanges objects in the same rda file, but for
some reason, one of the smaller GRanges objects (~23Mb) makes the saved
file go from 25Mb to 9Gb+ and I'm unsure of why exactly, and have never
seen this problem before:

> class(exons)
[1] "GRanges"
attr(,"package")
[1] "GenomicRanges"
> class(utr5seg)
[1] "GRanges"
attr(,"package")
[1] "GenomicRanges"
> class(utr3seg)
[1] "GRanges"
attr(,"package")
[1] "GenomicRanges"
> class(introns)
[1] "GRanges"
attr(,"package")
[1] "GenomicRanges"
> save(exons, utr5seg, utr3seg, trans, tInfo, t2g, # introns,
 file="annotation-tables-forRNAseq.rda")

the resulting saved object size in my directory is 23mb

> print(object.size(introns),units="Mb")
22.9 Mb

but when i include this `introns` GRanges object by running:

save(exons, utr5seg, utr3seg, trans, tInfo, t2g, introns,
file="annotation-tables-forRNAseq.rda")

the object size in my directory got up to 9Gb, and I have to kill the save.
any idea whats going on??

> introns
GRanges with 691807 ranges and 2 metadata columns:
           seqnames               ranges strand   |       tx_id
              <Rle>            <IRanges>  <Rle>   | <character>
       [1]     chr1     [ 12228,  12645]      +   |       1,2,3
       [2]     chr1     [ 12698,  13402]      +   |       1,2,3
       [3]     chr1     [322229, 324287]      +   |           7
       [4]     chr1     [324346, 324438]      +   |           7
       [5]     chr1     [324061, 324287]      +   |           8
       ...      ...                  ...    ... ...         ...
  [691803]     chrY [27216989, 27218792]      -   |       76941
  [691804]     chrY [27218869, 27245878]      -   |       76941
  [691805]     chrY [27329896, 27330860]      -   |       76942
  [691806]     chrY [59359509, 59360006]      -   |       76950
  [691807]     chrY [59360116, 59360500]      -   |       76950
                                    tx_name
                                <character>
       [1] uc001aaa.3,uc010nxq.1,uc010nxr.1
       [2] uc001aaa.3,uc010nxq.1,uc010nxr.1
       [3]                       uc009vjk.2
       [4]                       uc009vjk.2
       [5]                       uc001aau.3
       ...                              ...
  [691803]                       uc011nbv.2
  [691804]                       uc011nbv.2
  [691805]                       uc004fwt.3
  [691806]                       uc011ncc.1
  [691807]                       uc011ncc.1
  ---
  seqlengths:
        chr1      chr2      chr3      chr4 ...     chr22      chrX      chrY
   249250621 243199373 198022430 191154276 ...  51304566 155270560  59373566


Thanks a ton,
Andrew

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