3.Complementing a Strand of DNA

Problem

In DNA strings, symbols 'A' and 'T' are complements of each other, as are 'C' and 'G'.

The reverse complement of a DNA string ss is the string scsc formed by reversing the symbols of ss, then taking the complement of each symbol (e.g., the reverse complement of "GTCA" is "TGAC").

Given: A DNA string ss of length at most 1000 bp.

Return: The reverse complement scsc of ss.

Sample Dataset

AAAACCCGGT

Sample Output

ACCGGGTTTT

# -*- coding: utf-8 -*-
"""
Created on Thu Dec 08 20:33:16 2016

@author: hyl
“””
alt_map = {'ins':'0'}
complement = {'A': 'T', 'C': 'G', 'G': 'C', 'T': 'A'} 

def reverse_complement(seq):    
    for k,v in alt_map.iteritems():
        seq = seq.replace(k,v)
    bases = list(seq) 
    bases = reversed([complement.get(base,base) for base in bases])
    bases = ''.join(bases)
    for k,v in alt_map.iteritems():
        bases = bases.replace(v,k)
    print bases
if __name__ == "__main__":
    fh= open ("C:\Users\hyl\Desktop\rosalind_revc.txt")
    seq =''
    for line in fh.readlines():
        seq += line
    reverse_complement(seq)