[BioC] endoapply over GRangesList fails when an empty GRanges object is returned (Bug?)

[Steve Lianoglou]

Hi all,

I think this is the wrong behavior .. an endoapply(GRangesList,
function(...)) will fail if the embedded function returns and empty
GRanges object as one of its operations.

Calling GRangesList(lapply(GRangesList, function(...))) will work.
So too would an endoapply over an IRangesList that does the same thing ...

In the code below -- the result that's meant to be stored in "fail" is
what I'm talking about. The other two code blocks is just to show you
that it works if you do an end-around of the endoapply(GRangesList,
...).

I think I would expect the result that comes back in "good" down below
to be the same thing that "fail" should be.


  gr <- GRanges(seqnames='chr1', strand='+',
                ranges=IRanges(start=c(sample(18:22, 10, replace=TRUE),
                                 sample(100:108, 10, replace=TRUE)),
                  width=sample(18:20, 20, replace=TRUE)))
  strand(gr)[2:5] <- '-'
  grl <- split(gr, strand(gr))

  itake <- IRanges(start=100, end=150)
  gtake <- GRanges(seqnames='chr1', ranges=itake)

  ## This will fail, don't think it should
  fail <- endoapply(grl, function(x) {
    subsetByOverlaps(x, gtake)
  })

  ## This works, and ultimately is what the previous one should be
  good <- GRangesList(lapply(grl, function(x) {
    take <- GRanges(seqnames='chr1', ranges=itake)
    subsetByOverlaps(x, gtake)
  }))

  ## Test IRangesList: this works.
  irl <- IRangesList(lapply(grl, ranges))
  check <- endoapply(irl, function(x) {
    subsetByOverlaps(x, itake)
  })

Thanks,
-steve

R version 2.12.0 Under development (unstable) (2010-08-18 r52771)
Platform: x86_64-apple-darwin10.4.0/x86_64 (64-bit)

locale:
[1] en_US.UTF-8/en_US.UTF-8/C/C/en_US.UTF-8/en_US.UTF-8

attached base packages:
[1] grid      stats     graphics  grDevices utils     datasets
methods   base

other attached packages:
 [1] org.Hs.eg.db_2.4.1                 AnnotationDbi_1.11.4
 [3] Biobase_2.9.0                      BSgenome.Hsapiens.UCSC.hg18_1.3.16
 [5] ggplot2_0.8.8                      proto_0.3-8
 [7] reshape_0.8.3                      doMC_1.2.1
 [9] multicore_0.1-3                    foreach_1.3.0
[11] codetools_0.2-2                    iterators_1.0.3
[13] GenomeGraphs_1.9.0                 biomaRt_2.5.1
[15] bitops_1.0-4.1                     Rsamtools_1.1.12
[17] data.table_1.5                     plyr_1.1
[19] BSgenome_1.17.6                    Biostrings_2.17.28
[21] RSQLite_0.9-2                      DBI_0.2-5
[23] GenomicFeatures_1.1.11             GenomicRanges_1.1.20
[25] IRanges_1.7.19

loaded via a namespace (and not attached):
[1] RCurl_1.4-3       rtracklayer_1.9.7 tools_2.12.0      XML_3.1-1

-- 
Steve Lianoglou
Graduate Student: Computational Systems Biology
 | Memorial Sloan-Kettering Cancer Center
 | Weill Medical College of Cornell University
Contact Info: http://cbio.mskcc.org/~lianos/contact