Extract unique combinations of columns (number 1 to 4) in a tab separated file.

uinique_values.py

with open('sample.txt') as fi:
    dct = {}
    header = fi.readline()
    """Couldn't figure what this row is for
    """
    rec1 = fi.readline()
    for line in fi.readlines():
        x = line.split()[1:5]
        key = ",".join(x)
        dct[key] = dct.get(key, 0) + 1

with open('out.txt','w') as fout:
    for k in dct.keys():
        fout.write(k.replace(",","\t"))
        fout.write("\n")