Krypto_Grundlagen/utils/CipherUtils.py

from utils import AlphabetUtils as au

GERMAN_FREQUENCY_PROFILE = [
		0.0651,
		0.0189,
		0.0306,
		0.0508,
		0.1740,
		0.0166,
		0.0301,
		0.0476,
		0.0755,
		0.0027,
		0.0121,
		0.0344,
		0.0253,
		0.0978,
		0.0251,
		0.0079,
		0.0002,
		0.0700,
		0.0727,
		0.0615,
		0.0435,
		0.0067,
		0.0189,
		0.0003,
		0.0004,
		0.0113
	]


def calculate_frequency(text: str, fancy_printing: bool = False):
	"""
	Calculates the frequency of every letter in the german alphabet for the given text
	:param text: The text to calculate the letter frequency for
	:param fancy_printing: Whether to print the frequencies to the console
	:return: A list of frequencies, where index 0 contains the frequency of a in percent and so on.
	"""
	occurrence_count = [0 for i in range(26)]

	for char in text:
		if au.is_letter_of_alphabet(char):
			char_index = au.get_index_of_letter(char)
			occurrence_count[char_index] += 1

	occurrence_frequency = []

	for count in occurrence_count:
		occurrence_frequency.append(count / len(text))

	if fancy_printing:
		for i in range(26):
			print(f'{au.get_letter_at_index(i, True)}: {occurrence_frequency[i] * 100}%')

	return occurrence_frequency


def transform_invalid_chars(input: str) -> str:
	"""
	Transforms invalid characters like german umlauts into their allowed alternatives
	:param input: The text to check
	:return: The improved text
	"""
	res = input
	res = res.replace('ä', 'ae')
	res = res.replace('A', 'Ae')
	res = res.replace('ö', 'oe')
	res = res.replace('Ö', 'Oe')
	res = res.replace('ü', 'ue')
	res = res.replace('Ü', 'Ue')
	res = res.replace('ß', 'ss')

	return res


if __name__ == '__main__':
	print(
		calculate_frequency('Hier den Text eingeben, für den die Wahrscheinlichkeiten berechnet werden sollen', True))