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I want to compute the depth of coverage only for specific intervals in phase 3, 1000 genomes project.I have not worked with 1000 genomes project before, so a bit unfamiliar with it. I do not want to download all of the bam files for the entire genomic region, just those intervals which I am interested in them. I guess I can use this (I found from biostars forum)

samtools -bu view 'http://ftp.1000genomes.ebi.ac.uk/vol1/ftp/phase3/data/HG01375/alignment/HG01375.mapped.ILLUMINA.bwa.CLM.low_coverage.20120522.bam' "2:1000000-2000000" | (...)

However, I am just a bit confused. First of all, when I try the code above directly from the command line, I get an error message "No such file or directory"! Am I doing something wrong? or should I provide a specific path? Second, I want to run it for the mapped files for all individuals: *.bam”. through a loop.

Can anyone help me to solve my problem?

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The command you're looking for is:

samtools view -c http://ftp.1000genomes.ebi.ac.uk/vol1/ftp/phase3/data/HG01375/alignment/HG01375.mapped.ILLUMINA.bwa.CLM.low_coverage.20120522.bam 2:1000000-2000000

For a series of intervals, you'd be better off scripting something with pysam:

import pysam
bam = pysam.AlignmentFile("some file.bam")
regions = open("your regions.bed")
for region in regions:
    chrom, start, end = region.split("\t")
     bam.count(chrom, int(start), int(end))  # Do something with the result

You might see if there are bigWig files available, they'd be faster to process.

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  • $\begingroup$ ,thanks. I could rum the sam tools command for a single file. Thanks for the pysam, I will try it. But do you know how can I run a samtools command through a loop? just to remind that I do not have bam files downloaded. $\endgroup$
    – Anna1364
    Apr 23 '18 at 21:18
  • $\begingroup$ You can do for loops in bash. It can be pretty painful to script anything complicated in bash, though. $\endgroup$
    – Devon Ryan
    Apr 23 '18 at 21:20
  • $\begingroup$ yes, I know the for loop solution. my problem is that the bam files for each individual are in separate folders. I am trying this: for file in ftp.1000genomes.ebi.ac.uk/vol1/ftp/phase3/data*/alignment/*.bam; do /data/programs/samtools-1.3.1/samtools view -c "${file}" 2:1000000-2000000 done but get an error message. $\endgroup$
    – Anna1364
    Apr 23 '18 at 21:46
  • $\begingroup$ You can't wild-card URLs, you'll need to provide them as a list. $\endgroup$
    – Devon Ryan
    Apr 23 '18 at 22:17
  • $\begingroup$ @Anna1364 please add all this information to your question. We can't answer you if you don't tell us all the details. Give us a list of the files you want to read and explain what you need to do with those files. $\endgroup$
    – terdon
    Apr 24 '18 at 8:18

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