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how to split a coordinate-sorted bam file by read group

Hi, I have a coordinate-sorted bam file, and its read group information in the header is:

@RG ID:0 PL:ILLUMINA SM:COLO829_Normal_Tgen PU:H0CGCADXX:1:none

@RG ID:1 PL:ILLUMINA SM:COLO829_Normal_Tgen PU:H0CGCADXX:2:none

@RG ID:2 PL:ILLUMINA SM:COLO829_Normal_Tgen PU:H0CGCADXX:3:none

@RG ID:3 PL:ILLUMINA SM:COLO829_Normal_Tgen PU:H0CGCADXX:4:none

@RG ID:4 PL:ILLUMINA SM:COLO829_Normal_Tgen PU:H0CGCADXX:5:none

@RG ID:5 PL:ILLUMINA SM:COLO829_Normal_Tgen PU:H0CGCADXX:6:none

@RG ID:6 PL:ILLUMINA SM:COLO829_Normal_Tgen PU:H0CGCADXX:7:none

@RG ID:7 PL:ILLUMINA SM:COLO829_Normal_Tgen PU:H0CGCADXX:8:none

I want to extract only the reads with ID:0, and I tried commands:

samtools view -b bam -r '@RG\tID:0\tPL:ILLUMINA\tSM:COLO829_Normal_Tgen\tPU:H0CGCADXX:1:none' ~/mixted.bam > rg_0.bam

and 

samtools split -f '@RG\tID:0\tPL:ILLUMINA\tSM:COLO829_Normal_Tgen\tPU:H0CGCADXX:1:none' ~/mixted.bam > rg_0.bam

I just got the header information in the output bam file.

Can someone help me with this? Thank you!

sequencing
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updated by finswimmer finswimmer • written by jing.mengrabbit • jing.mengrabbit

1 answer

Hello jing.mengrabbit,

you are using the command incorrect. You must pass the ID value of the the RG line to samtools view.

$ samtools view -b -r 0 ~/mixted.bam > rg_0.bam

samtools split have no option to just get one read group. It creates a new file for each read group it finds.

samtools split [options] merged.sam|merged.bam|merged.cram

Splits a file by read group.

Options:

-u FILE1
Put reads with no RG tag or an unrecognised RG tag into FILE1

-u FILE1:FILE2
As above, but assigns an RG tag as given in the header of FILE2

-f STRING
Output filename format string (see below) ["%*_%#.%."]

-v
Verbose output

fin swimmer

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written by finswimmer finswimmer

Fine if I could help you.

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fin swimmer

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written by finswimmer finswimmer

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