How to get average coverage from BAM files?

[Martino]

Hi,

I have a major DNA database of many BAM files.

Now, I would like to know the average coverage of each BAM file. Then, I can rank all those BAM files with on number 1 the BAM file with the highest average coverage.

My question is: Does someone know how to get the average coverage of a BAM file in its fastest way?

[dariober]

What do you mean exactly by coverage? Is it just the total number of mapped reads divided by the size of the reference genome? If so you could get the number of mapped reads with:

samtools view -c -F 4 myfile.bam

And divide this number by the genome size.

If the bam files are indexed the fastest way to get the number of mapped reads on each chromosome is:

samtools idxstats myfile.bam

All the best
Dario

[SeekAnswers]

GATK DepthOfCoverage module should do this for you and its pretty neat to use.