I am trying to do quality control of gene expression data. I am running a script to get sample info,tissues and sequencing method used from SampleattributesDS.txt file. The script:

#!/bin/bash/python
from collections import defaultdict
import gzip

def get_ids_from_vcf(vcf_file):
    with gzip.open(vcf_file) as fh:
        for line in fh:
            line = line.decode('utf-8')
            if not line.startswith("##"):
                break
        sample_ids = line.strip().split()[9:]
        return set(sample_ids)

vcf_file = '/new_rna-seq/quality_Control/chr22_annotate.vcf.gz'
vcf_sample_ids = get_ids_from_vcf(vcf_file)
tissue_donors = defaultdict(list)

samples_file = '/new_rna-seq/quality_Control/GTEx_Analysis_v8_Annotations_SampleAttributesDS.txt'

with open(samples_file) as fh:
    hdr = fh.readline() # Drop header
    for line in fh:
        if line == '' or line == '\n':
            continue
        fields = line.strip().split('\t')
        sample_id = fields[0]
        tissue = fields[13]
        frz = fields[26]
        donor_id = '-'.join(sample_id.split('-')[:2])
        if donor_id in vcf_sample_ids and frz == 'RNASEQ':
            tissue_donors[tissue].append(sample_id + '\n')

for tissue in tissue_donors:
    with open(tissue.replace(' - ', '_').replace(' ', '_') + '_donors.txt', 'w') as fh:
        fh.writelines(tissue_donors[tissue])

While running this script: I am getting an error The error is:

python get_donors_by_tissue.py Traceback (most recent call last):
File "/home/TWAS/data_download/new_rna-seq/quality_Control/get_donors_by_tissue.py", line 28, in <module> frz = fields[30] IndexError: list index out of range

The error is pertaining to the file: GTEx_Analysis_v8_Annotations_SampleAttributesDS.txt I have downloaded this attribute file from this link: https://www.gtexportal.org/home/datasets wget https://storage.googleapis.com/gtex_analysis_v8/annotations/GTEx_Analysis_v8_Annotations_SampleAttributesDS.txt Could you anyone help me out with this? I am not able to understand how to get these info from this file