dna_suspects.py

sample = ['GTA','GGG','CAC']

def read_dna(dna_file):
  dna_data = ""
  with open(dna_file,"r") as f:
    for line in f:
      dna_data += line
  return dna_data

def dna_codons(dna):
  codons = []
  for item in range(0,len(dna),3):
    if (item+3) < len(dna):
      codons.append(dna[item: item + 3])
  return codons

def match_dna(dna):
  matches = 0
  for codon in dna:
    if codon in sample:
      matches += 1
  return matches

def is_criminal(dna_sample):
  dna_data = read_dna(dna_sample)
  codons = dna_codons(dna_data)
  num_matches = match_dna(codons)
  if num_matches >= 3:
    print "Number of matches: %d, the investigation should continue" % (num_matches)
  else:
    print "Number of matches: %d, suspect can be set free" % (num_matches)
    
is_criminal('suspect1.txt')
is_criminal('suspect2.txt')
is_criminal('suspect3.txt')