Writing VCF File using PyVCF [HELP]

[ravaan]

I am using PyVCF to read a VCF file, modify the data, and write this modified data either to the old file or to a new file. As given in their documentation I am using the vcf.Writer function to create a wrtieStream and write the file, code here:

vcf_reader = vcf.Reader(open('/home/ubuntu/GSoC-Strain_Diffrential/test.vcf.gz'))

# code to modify the data

vcf_writer = vcf.Writer(open('/dev/null', 'w'), vcf_reader)

count = 1
record = next(vcf_reader)
REF_list = [record.CHROM]
for record in vcf_reader:
    print record.REF, record.POS
    record.REF = 'C'
    print record.REF
    REF_list.extend([record.POS])
    vcf_writer.write_record(record)
    vcf_writer.flush()
    count = count + 1
    if count > 100:
        break

The code is running without any errors, but no changes are written to the file (The original file remains unchanged and no new file is created).

Any help is highly appreciated.

The complete code is provided here

[GenoMax]

Looks like the output is specified as (/dev/null = nothing). Change that to a real path/file name e.g. /home/ubuntu/GSoC-Strain_Diffrential/test_modified.vcf.gz

[ravaan]

I tried that earlier but got some error, tried again worked like charm! Thanks for the help!