Plotting metadata from GenomicRanges object

Question

I have a GRanges object with metadata that I want to plot. Many of the online tutorials which manipulate these GRanges for plotting show how to plot the main columns (chromosome,start/end,strand) but nothing to plot the metadata as a function of the position in each row.

How precisely should I do this? Ideally, I would like to plot metadata from multiple GRanges objects on the same plot to compare them.

EDIT (following comment):

GRanges object with 6 ranges and 140 metadata columns:
      seqnames        ranges strand |
         <Rle>     <IRanges>  <Rle> |
  [1]     chr1 100000-199999      * |
  [2]     chr1 400000-499999      * |
  [3]     chr1 600000-699999      * |
  [4]     chr1 700000-799999      * |
  [5]     chr1 800000-899999      * |
  [6]     chr1 900000-999999      * |
                  eigen   domain         arm
              <numeric> <factor> <character>
  [1] -1.62475825405065     open          1p
  [2] -1.62475825405065     open          1p
  [3] -1.62475825405065     open          1p
  [4] -1.62475825405065     open          1p
  [5] -1.63354915136132     open          1p
  [6]  -1.6322733358426     open          1p
      exon.fraction       gc     short      long
          <numeric> <matrix> <numeric> <numeric>
  [1]       0.02968  0.45815         0         0
  [2]       0.04305  0.40192         0         0
  [3]       0.00959  0.42091         0         0
  [4]       0.04593  0.43337         0         1
  [5]       0.02425  0.44822         2         1
  [6]       0.16977  0.62123        27        56
         nfrags             ratio   short.corrected
      <numeric>         <numeric>         <numeric>
  [1]         0               NaN              <NA>
  [2]         0               NaN              <NA>
  [3]         0               NaN              <NA>
  [4]         1                 0 -3.50822623240367
  [5]         3                 2  2.81796238367926
  [6]        83 0.482142857142857  39.8824095079959
...

My question regards plotting a column like eigen as a function of the position (given by seqnames and ranges)

Answer 1

You can access the data.frame just using $. All of them can be accessed using values() . Something like this:

library(GenomicRanges)
gr = GRanges(seqnames=1,IRanges(start=1:10,width=1))
values(gr) = data.frame(eigen=rnorm(10),ratio=runif(10))

plot(start(gr),gr$eigen)

or

plot(start(gr),values(gr)$eigen)