On 09/23/2011 02:57 PM, rohan bareja wrote:
> Hi,
>
> utr=threeUTRsByTranscript(txdb,use.names=FALSE)
> So,utr is GRangesList of length 33381
> Then as u said,I did the following:
>
> txBygene <- transcriptsBy(txdb, "gene")
> geneID <- rep(names(txBygene), elementLengths(txBygene))
> df <- data.frame(geneID=geneID,
> txID=values(unlist(txBygene))[["tx_id"]])
>
> This gives me a dataframe with 40,780 rows with gene ID and txID from
> txBygene object.
> geneID txID
> 40775 9994 11731
> 40776 9994 11730
> 40777 9997 38491
> 40778 9997 38489
> 40779 9997 38496
> 40780 9997 38497
>
> Since my utr object is of length 33,381 ,my counts length is same i.e
> 33,381
> So I am not able to map the counts to the above data frame which has
> transcript and gene IDs.
>
Yes, these lengths are different.
In this example we have utr regions from 58 transcripts.
> length(utr)
[1] 58
Those 58 transcripts can be matched to their gene ID's by looking at the
txBygene object. All of the transcripts fall into one (or more) of 51
genes,
> length(txBygene)
[1] 51
There are multiple transcripts per gene so we expand the gene ID's to
map to the transcripts.
> dim(df)
[1] 79 2
This data.frame has all transcripts from the txdb mapped to the gene
ID's. Your utr data may contain only a subset of these transcripts. That
is something you need to check. Match the desired transcript names to
the df, pull out the gene IDs. You then have the gene ID's for your utr
regions and can split or group your counts by gene.
Valerie
>
>
>
> --- On *Fri, 23/9/11, Valerie Obenchain /<voben...@fhcrc.org>/*wrote:
>
>
> From: Valerie Obenchain <voben...@fhcrc.org>
> Subject: Re: [Bioc-sig-seq] Reads in 3'utr
> To: "rohan bareja" <rohan_1...@yahoo.co.in>
> Cc: bioc-sig-sequencing@r-project.org
> Date: Friday, 23 September, 2011, 10:50 PM
>
> Hi Rohan,
>
> You can relate the counts for 3UTR regions to gene IDs through the
> transcript IDs.
>
> txdb_file <- system.file("extdata",
> "UCSC_knownGene_sample.sqlite", package="GenomicFeatures")
> txdb <- loadFeatures(txdb_file)
> utr=threeUTRsByTranscript(txdb,use.names=FALSE)
>
>
> The transcript names can be matched to the gene ID's through,
>
> txBygene <- transcriptsBy(txdb, "gene")
> geneID <- rep(names(txBygene), elementLengths(txBygene))
> df <- data.frame(geneID=geneID,
> txID=values(unlist(txBygene))[["tx_id"]])
>
> Now you know what gene ID each tx count belongs to. You can split
> your counts by gene ID ...
>
>
> Valerie
>
>
>
> On 09/20/2011 12:13 PM, rohan bareja wrote:
>> Hi everyone,
>> I am doing NGS analysis using bam files.I have counted reads in 3'utr
>> region using
>> utr=threeUTRsByTranscript(txdb,use.names=FALSE)
>> countsUTR<- countOverlaps(utr,reads)
>> I have got the transcript level counts from this.How can I get the gene
>> level counts??It might sound silly but Does anybody have an idea on what
>> type of anaylses we can do from this countsUTR ?
>> Thanks,Rohan
>> [[alternative HTML version deleted]]
>>
>>
>>
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>
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