On Tue, Sep 29, 2009 at 7:23 PM, Michael Lawrence <[email protected]>wrote:

>
>
> On Tue, Sep 29, 2009 at 4:28 PM, Seidel, Christopher <[email protected]>wrote:
>
>> Hello,
>>
>> In an earlier thread: BED to WIG format conversion (Thu 9/17/2009 4:50 PM)
>> Michael Lawrence mentioned:
>>
>> Ignoring efficiency, it's pretty straight-forward. In the development
>> version of IRanges, one can convert an Rle (or RleList for multiple
>> chromosomes) as output to coverage() to a RangedData. In the development
>> version of rtracklayer, this is done implicitly:
>>
>> > export(cov, "coverage.wig")
>>
>> as a way to create a wig file from a coverage() result. When I try this,
>> my wig file looks like the following:
>>
>> track name="R Track" type=wiggle_0
>> .       0       2       168
>> .       2       4       175
>> .       4       5       177
>> .       5       7       178
>> .       7       8       182
>> .       8       12      185
>> .       12      14      188
>> .       14      15      191
>> etc.
>>
>> This isn't compatible with any of the UCSC wig formats that I'm aware of
>> (is it?).
>
>
> No, it should be outputting the chromosome names instead of ".", following
> the BED-line WIG variant.
>
> The coercion from Rle to RangedData yields a single-chromosome RangedData
> with NULL names. This becomes <NA> upon coercion to a UCSCData (which tries
> to generate conforming names but fails). <NA> shows up as "." in BED.
>
> New policy: RangedData cannot have NULL names. Made a validity check for
> this. Fixed Rle->RangedData coercion to yield default of "1". This mimics
> the behavior of RangedData().
>
> Shouldn't rtracklayer be putting out a variableStep format for this?
>
>
> Well, come to think of it, that should be possible. Right now, rtracklayer
> only uses variableStep when the span is the same across an entire
> chromosome. Should be possible to split the chromosome into multiple blocks
> though.
>

I just made this work. It generates much smaller WIG files for coverage-like
tracks. Thanks for the suggestion.

Michael


>
>
>> Am I doing something wrong?
>>
>>
>
> Note that in general your code will not work, because you do not tell
> rtracklayer the name of the chromosome. This makes me worry that generating
> a default chromosome name will often hide user errors.
>
>
>
>> By the way, here is my work flow for going from solexa export to coverage:
>>
>> # read in some IP data
>> aln <- readAligned(spath, pattern="s_1_export.txt", type="SolexaExport",
>> filter=filt)
>> # convert to GenomeData object
>> s1 <- as(aln,"GenomeData")
>>
>> # read in some WCE data
>> aln <- readAligned(spath, pattern="s_3_export.txt", type="SolexaExport",
>> filter=filt)
>> # convert to GenomeData object
>> s3 <- as(aln,"GenomeData")
>>
>> # create GenomeDataList from ip and wce
>> ypd <- GenomeDataList(list(ip=s1, wce=s3))
>>
>> # extend reads
>> ip1 <- extendReads(ypd$ip$chrI, seqLen=150)
>> wce1 <- extendReads(ypd$wce$chrI, seqLen=150)
>>
>> # find coverage for chromosome 1
>> ip1.cov <- coverage(ip1, width=230208)
>> wce1.cov <- coverage(wce1, width=230208)
>>
>> # make a track
>> export(ip1.cov, "ip1_coverage.wig")
>>
>> > sessionInfo()
>> R version 2.10.0 Under development (unstable) (2009-09-03 r49555)
>> x86_64-unknown-linux-gnu
>>
>> locale:
>> [1] C
>>
>> attached base packages:
>> [1] stats     graphics  grDevices utils     datasets  methods   base
>>
>> other attached packages:
>> [1] rtracklayer_1.5.13 RCurl_1.2-0        bitops_1.0-4.1
>> chipseq_0.1.25
>> [5] ShortRead_1.3.34   lattice_0.17-25    BSgenome_1.13.11
>> Biostrings_2.13.39
>> [9] IRanges_1.3.75
>>
>> loaded via a namespace (and not attached):
>> [1] Biobase_2.5.6 XML_2.6-0     grid_2.10.0   hwriter_1.1
>>
>> -Chris
>>
>> Chris Seidel, Ph.D.
>> http://research.stowers-institute.org/cws
>>
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>>
>
>

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