# Given a string 'str', this counts all substrings with length 2 and print them def countsubstrings(str): dict = {} # dictionary: key => substring , value => its frequency for i in range(len(str)): substr = str[i:i+2] # substring with length 2 if len(substr) < 2: continue # substr must have at least two length if dict.has_key(substr): dict[substr] = dict[substr] + 1 else: dict[substr] = 1 return(dict) if __name__ == '__main__': import sys str = sys.argv[1] # print str # for debug dict = countsubstrings(str) print dict # for debug # sort dictionaries # print all substrings for (v, k) in array: print k, " occurs ", v, " times"