Adding util methode for letter frequency

utils/AlphabetUtils.py

@@ -2,7 +2,22 @@ LETTERS = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N',
 		   'W', 'X', 'Y', 'Z']
 
 
+def is_letter_of_alphabet(letter: str):
+	"""
+	Checks if the given letter is a valid letter of the alphabet
+	:param letter: The letter to check
+	:return: If the letter is in the alphabet
+	"""
+	return letter.upper() in LETTERS
+
+
 def get_letter_at_index(idx: int, capital: bool = False):
+	"""
+	Returns the letter at the given index
+	:param idx: The index of the letter to return
+	:param capital: If the capitalized letter should be returned
+	:return: The letter
+	"""
 	if idx < 0 or idx > 25:
 		raise AttributeError
 
@@ -10,6 +25,11 @@ def get_letter_at_index(idx: int, capital: bool = False):
 
 
 def get_index_of_letter(letter: str):
+	"""
+	Returns the index of the given letter
+	:param letter: The letter to return the index of
+	:return: The index of the letter
+	"""
 	if letter.upper() not in LETTERS:
 		raise AttributeError
 

utils/CipherUtils.py

@@ -0,0 +1,31 @@
+import AlphabetUtils as au
+
+
+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
+	: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
+
+
+if __name__ == '__main__':
+	print(
+		calculate_frequency('Hier den Text eingeben, für den die Wahrscheinlichkeiten berechnet werden sollen', True))