Coverage Question: GenomicRanges
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@lakshmanan-iyer-1829
Last seen 9.3 years ago
United States
I am calculating the coverage on a subset of a gapped aliment that obtained using "subsetByOverlaps" between a "GappedAlignments" and a "GRanges" object #> class (Dendaligns) #[1] "GappedAlignments" #attr(,"package") #[1] "GenomicRanges" #> class (p3UTRsChr) #[1] "GRanges" #attr(,"package") #[1] "GenomicRanges" DendfiltData2 <- subsetByOverlaps (Dendaligns, p3UTRsChr); #> class (DendfiltData2) #[1] "GappedAlignments" #attr(,"package") #[1] "GenomicRanges" # # Find coverage Dendcov <- coverage(DendfiltData2) # # Find islands of coverage with min value of 1 Dendislands <- slice (Dendcov, lower=1); # # convert the island ranges in to a data frame DendislandsData <- as.data.frame (ranges(Dendislands[[chr]]) ); # # extract the scores of the coverage in a list Dendisland_scores <- viewApply (Dendislands[[chr]], function (x) as.integer(x)) When I look at the scores, the first island contains a series of 1 (45 of them in my case). However, when I visualize the same regions in IGV with the raw bam file (see attached picture), I see that the counts are > 1 for bases after first 10 bases. I am wondering where the counting becomes different from summing up the reads at any position! Thanks for any thoughts -best -Lax -------------- next part -------------- A non-text attachment was scrubbed... Name: igv_panel.png Type: image/png Size: 6317 bytes Desc: not available URL: <https: stat.ethz.ch="" pipermail="" bioconductor="" attachments="" 20120309="" 93fcaa7e="" attachment.png="">
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@michael-lawrence-3846
Last seen 3.1 years ago
United States
One possibility is that you need to use ignore.strand = TRUE in your subsetByOverlaps call, i.e., you are filtering out all of those negative strand reads. Michael On Fri, Mar 9, 2012 at 9:29 AM, Lakshmanan Iyer <laxvid@gmail.com> wrote: > I am calculating the coverage on a subset of a gapped aliment that obtained > using "subsetByOverlaps" between a "GappedAlignments" and a "GRanges" > object > #> class (Dendaligns) > #[1] "GappedAlignments" > #attr(,"package") > #[1] "GenomicRanges" > #> class (p3UTRsChr) > #[1] "GRanges" > #attr(,"package") > #[1] "GenomicRanges" > DendfiltData2 <- subsetByOverlaps (Dendaligns, p3UTRsChr); > #> class (DendfiltData2) > #[1] "GappedAlignments" > #attr(,"package") > #[1] "GenomicRanges" > # > # Find coverage > Dendcov <- coverage(DendfiltData2) > # > # Find islands of coverage with min value of 1 > Dendislands <- slice (Dendcov, lower=1); > # > # convert the island ranges in to a data frame > DendislandsData <- as.data.frame (ranges(Dendislands[[chr]]) ); > # > # extract the scores of the coverage in a list > Dendisland_scores <- viewApply (Dendislands[[chr]], function (x) > as.integer(x)) > > When I look at the scores, the first island contains a series of 1 (45 of > them in my case). > However, when I visualize the same regions in IGV with the raw bam file > (see attached picture), I see that the counts are > 1 for bases after first > 10 bases. > > I am wondering where the counting becomes different from summing up the > reads at any position! > > Thanks for any thoughts > -best > -Lax > > _______________________________________________ > Bioconductor mailing list > Bioconductor@r-project.org > https://stat.ethz.ch/mailman/listinfo/bioconductor > Search the archives: > http://news.gmane.org/gmane.science.biology.informatics.conductor > [[alternative HTML version deleted]]
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You are right. From the picture attached, I could see that only the first read is on + strand, the other three are - strand and are being ignored. Let me rerun and see Best Lax Sent from my iPhone On Mar 9, 2012, at 1:05 PM, Michael Lawrence <lawrence.michael@gene.com> wrote: > One possibility is that you need to use ignore.strand = TRUE in your subsetByOverlaps call, i.e., you are filtering out all of those negative strand reads. > > Michael > > On Fri, Mar 9, 2012 at 9:29 AM, Lakshmanan Iyer <laxvid@gmail.com> wrote: > I am calculating the coverage on a subset of a gapped aliment that obtained > using "subsetByOverlaps" between a "GappedAlignments" and a "GRanges" object > #> class (Dendaligns) > #[1] "GappedAlignments" > #attr(,"package") > #[1] "GenomicRanges" > #> class (p3UTRsChr) > #[1] "GRanges" > #attr(,"package") > #[1] "GenomicRanges" > DendfiltData2 <- subsetByOverlaps (Dendaligns, p3UTRsChr); > #> class (DendfiltData2) > #[1] "GappedAlignments" > #attr(,"package") > #[1] "GenomicRanges" > # > # Find coverage > Dendcov <- coverage(DendfiltData2) > # > # Find islands of coverage with min value of 1 > Dendislands <- slice (Dendcov, lower=1); > # > # convert the island ranges in to a data frame > DendislandsData <- as.data.frame (ranges(Dendislands[[chr]]) ); > # > # extract the scores of the coverage in a list > Dendisland_scores <- viewApply (Dendislands[[chr]], function (x) > as.integer(x)) > > When I look at the scores, the first island contains a series of 1 (45 of > them in my case). > However, when I visualize the same regions in IGV with the raw bam file > (see attached picture), I see that the counts are > 1 for bases after first > 10 bases. > > I am wondering where the counting becomes different from summing up the > reads at any position! > > Thanks for any thoughts > -best > -Lax > > _______________________________________________ > Bioconductor mailing list > Bioconductor@r-project.org > https://stat.ethz.ch/mailman/listinfo/bioconductor > Search the archives: http://news.gmane.org/gmane.science.biology.informatics.conductor > [[alternative HTML version deleted]]
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