@@ -0,0 +1,68 @@
+# Frequency Finder
+
+# frequency taken from http://en.wikipedia.org/wiki/Letter_frequency
+englishLetterFreq = {'E': 12.70, 'T': 9.06, 'A': 8.17, 'O': 7.51, 'I': 6.97,
+'N': 6.75, 'S': 6.33, 'H': 6.09, 'R': 5.99, 'D': 4.25,
+'L': 4.03, 'C': 2.78, 'U': 2.76, 'M': 2.41, 'W': 2.36,
+'F': 2.23, 'G': 2.02, 'Y': 1.97, 'P': 1.93, 'B': 1.29,
+'V': 0.98, 'K': 0.77, 'J': 0.15, 'X': 0.15, 'Q': 0.10,
+'Z': 0.07}
+ETAOIN = 'ETAOINSHRDLCUMWFGYPBVKJXQZ'
+LETTERS = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
+
+def getLetterCount(message):
+letterCount = {'A': 0, 'B': 0, 'C': 0, 'D': 0, 'E': 0, 'F': 0, 'G': 0, 'H': 0,
+'I': 0, 'J': 0, 'K': 0, 'L': 0, 'M': 0, 'N': 0, 'O': 0, 'P': 0,
+'Q': 0, 'R': 0, 'S': 0, 'T': 0, 'U': 0, 'V': 0, 'W': 0, 'X': 0,
+'Y': 0, 'Z': 0}
+for letter in message.upper():
+if letter in LETTERS:
+letterCount[letter] += 1
+
+return letterCount
+
+def getItemAtIndexZero(x):
+return x[0]
+
+def getFrequencyOrder(message):
+letterToFreq = getLetterCount(message)
+freqToLetter = {}
+for letter in LETTERS:
+if letterToFreq[letter] not in freqToLetter:
+freqToLetter[letterToFreq[letter]] = [letter]
+else:
+freqToLetter[letterToFreq[letter]].append(letter)
+
+for freq in freqToLetter:
+freqToLetter[freq].sort(key = ETAOIN.find, reverse = True)
+freqToLetter[freq] = ''.join(freqToLetter[freq])
+
+freqPairs = list(freqToLetter.items())
+freqPairs.sort(key = getItemAtIndexZero, reverse = True)
+
+freqOrder = []
+for freqPair in freqPairs:
+freqOrder.append(freqPair[1])
+
+return ''.join(freqOrder)
+
+def englishFreqMatchScore(message):
+'''
+>>> englishFreqMatchScore('Hello World')
+1
+'''
+freqOrder = getFrequencyOrder(message)
+matchScore = 0
+for commonLetter in ETAOIN[:6]:
+if commonLetter in freqOrder[:6]:
+matchScore += 1
+
+for uncommonLetter in ETAOIN[-6:]:
+if uncommonLetter in freqOrder[-6:]:
+matchScore += 1
+
+return matchScore
+
+if __name__ == '__main__':
+import doctest
+doctest.testmod()