Finding unique combinations of two strings in python [duplicate]

Question

I have two strings:

StringA: ['K', 'T', 'T', 'T', 'K', 'K', 'G', 'T', 'T', 'T', 'T', 'K', 'K']

StringB: ['T', 'K', 'G', 'G', 'K', 'T', 'T', 'K', 'G', 'G', 'K', 'K', 'T']

And I want to test for how many unique combinations of letters there are. The strings are ordered, so I only want to match StringA position 1 with StringB position 1, StringA position 2 with StringB position 2, etc. So the pairs in the strings above are (KT), (TK), (TG), (TG), (KK), (KT), (GT), (TK), (TG), (TG), (TK), (KK), (KT).

And there are 5 unique combinations: (KT), (TK), (TG), (GT), (KK)

I have used the following code to produce the strings from two .csv files.

import sys
import csv

pairlist = open(sys.argv[1], 'r')
snp_file = open(sys.argv[2], 'r')

pair = csv.reader(pairlist, delimiter=',')
snps = csv.reader(snp_file, delimiter=',')

output = open(sys.argv[1]+"_FGT_Result", 'w')

snp1 = []
snp2 = []

firstpair = pair.next()

locusa = firstpair[0]
locusb = firstpair[1]

f = snps
        #search = snp.readlines()
for i, row in enumerate(f):
    if locusa in row:
        hita = row
        #print hita
        snp1.append(hita[2])
    if locusb in row:
        hitb = row
        #print hitb
        snp2.append(hitb[2])

print snp1
print snp2

pairlist.close()
snp_file.close()
output.close()

But I cannot figure out how to do the comparison. I have tried to convert the strings to sets, as I read in another thread, that this is required, but I am not sure why, and I cannot get it to work.

Answer 1

Just use zip and set to combine the two lists of strings and get unique combinations. I used a list comprehension to return combined strings:

>>> unique = [''.join(x)  for x in set(list(zip(StringA, StringB)))]
>>> unique
['TG', 'GT', 'KT', 'TK', 'KK']

Alternatively, if you simply want them in a set you can remove the list comprehension:

>>> unique = set(zip(StringA, StringB))
>>> unique
{('T', 'K'), ('T', 'G'), ('K', 'K'), ('K', 'T'), ('G', 'T')}