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95 lines
2.1 KiB
Python
95 lines
2.1 KiB
Python
# Frequency Finder
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import string
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# frequency taken from https://en.wikipedia.org/wiki/Letter_frequency
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english_letter_freq = {
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"E": 12.70,
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"T": 9.06,
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"A": 8.17,
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"O": 7.51,
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"I": 6.97,
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"N": 6.75,
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"S": 6.33,
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"H": 6.09,
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"R": 5.99,
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"D": 4.25,
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"L": 4.03,
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"C": 2.78,
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"U": 2.76,
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"M": 2.41,
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"W": 2.36,
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"F": 2.23,
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"G": 2.02,
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"Y": 1.97,
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"P": 1.93,
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"B": 1.29,
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"V": 0.98,
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"K": 0.77,
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"J": 0.15,
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"X": 0.15,
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"Q": 0.10,
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"Z": 0.07,
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}
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ETAOIN = "ETAOINSHRDLCUMWFGYPBVKJXQZ"
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LETTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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def get_letter_count(message: str) -> dict[str, int]:
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letter_count = {letter: 0 for letter in string.ascii_uppercase}
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for letter in message.upper():
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if letter in LETTERS:
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letter_count[letter] += 1
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return letter_count
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def get_item_at_index_zero(x: tuple) -> str:
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return x[0]
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def get_frequency_order(message: str) -> str:
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letter_to_freq = get_letter_count(message)
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freq_to_letter: dict[int, list[str]] = {
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freq: [] for letter, freq in letter_to_freq.items()
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}
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for letter in LETTERS:
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freq_to_letter[letter_to_freq[letter]].append(letter)
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freq_to_letter_str: dict[int, str] = {}
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for freq in freq_to_letter:
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freq_to_letter[freq].sort(key=ETAOIN.find, reverse=True)
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freq_to_letter_str[freq] = "".join(freq_to_letter[freq])
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freq_pairs = list(freq_to_letter_str.items())
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freq_pairs.sort(key=get_item_at_index_zero, reverse=True)
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freq_order: list[str] = [freq_pair[1] for freq_pair in freq_pairs]
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return "".join(freq_order)
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def english_freq_match_score(message: str) -> int:
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"""
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>>> english_freq_match_score('Hello World')
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1
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"""
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freq_order = get_frequency_order(message)
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match_score = 0
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for common_letter in ETAOIN[:6]:
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if common_letter in freq_order[:6]:
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match_score += 1
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for uncommon_letter in ETAOIN[-6:]:
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if uncommon_letter in freq_order[-6:]:
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match_score += 1
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return match_score
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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