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5 changes: 5 additions & 0 deletions .idea/.gitignore
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171 changes: 119 additions & 52 deletions exercise/ps4b.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,14 +5,15 @@

import string


### HELPER CODE ###
def load_words(file_name):
'''
file_name (string): the name of the file containing
the list of words to load

Returns: a list of valid words. Words are strings of lowercase letters.

Depending on the size of the word list, this function may
take a while to finish.
'''
Expand All @@ -26,14 +27,15 @@ def load_words(file_name):
print(" ", len(wordlist), "words loaded.")
return wordlist


def is_word(word_list, word):
'''
Determines if word is a valid word, ignoring
capitalization and punctuation

word_list (list): list of words in the dictionary.
word (string): a possible word.

Returns: True if word is in word_list, False otherwise

Example:
Expand All @@ -46,6 +48,7 @@ def is_word(word_list, word):
word = word.strip(" !@#$%^&*()-_+={}[]|\:;'<>?,./\"")
return word in word_list


def get_story_string():
"""
Returns: a story in encrypted text.
Expand All @@ -55,75 +58,99 @@ def get_story_string():
f.close()
return story


### END HELPER CODE ###

WORDLIST_FILENAME = 'words.txt'


class Message(object):
def __init__(self, text):
'''
Initializes a Message object

text (string): the message's text

a Message object has two attributes:
self.message_text (string, determined by input text)
self.valid_words (list, determined using helper function load_words)
'''
pass #delete this line and replace with your code here

self.message_text = text
self.valid_words = load_words(WORDLIST_FILENAME)
# pass #delete this line and replace with your code here

def get_message_text(self):
'''
Used to safely access self.message_text outside of the class

Returns: self.message_text
'''
pass #delete this line and replace with your code here
return self.message_text
# pass #delete this line and replace with your code here

def get_valid_words(self):
'''
Used to safely access a copy of self.valid_words outside of the class.
This helps you avoid accidentally mutating class attributes.

Returns: a COPY of self.valid_words
'''
pass #delete this line and replace with your code here
return self.valid_words.copy()
pass # delete this line and replace with your code here

def build_shift_dict(self, shift):
'''
Creates a dictionary that can be used to apply a cipher to a letter.
The dictionary maps every uppercase and lowercase letter to a
character shifted down the alphabet by the input shift. The dictionary
should have 52 keys of all the uppercase letters and all the lowercase
letters only.
shift (integer): the amount by which to shift every letter of the
letters only.

shift (integer): the amount by which to shift every letter of the
alphabet. 0 <= shift < 26

Returns: a dictionary mapping a letter (string) to
another letter (string).
Returns: a dictionary mapping a letter (string) to
another letter (string).
'''
pass #delete this line and replace with your code here
if shift not in range(0, 27):
raise ValueError("Invalid shift value")
alphabet = "abcdefghijklmnopqrstuvwxyz"
d1 = {ch: alphabet[i + shift - (len(alphabet))] for i, ch in enumerate(alphabet)}
alphabet = alphabet.upper()
d2 = {ch: alphabet[i + shift - (len(alphabet))] for i, ch in enumerate(alphabet)}
return {**d1, **d2}

pass # delete this line and replace with your code here

def apply_shift(self, shift):
'''
Applies the Caesar Cipher to self.message_text with the input shift.
Creates a new string that is self.message_text shifted down the
alphabet by some number of characters determined by the input shift
alphabet by some number of characters determined by the input shift

shift (integer): the shift with which to encrypt the message.
0 <= shift < 26

Returns: the message text (string) in which every character is shifted
down the alphabet by the input shift
'''
pass #delete this line and replace with your code here
d = self.build_shift_dict(shift)
l = []
for ch in self.get_message_text():
if ch in d.keys():
l.append(d[ch])
else:
l.append(ch)
return "".join(l)
# pass #delete this line and replace with your code here


class PlaintextMessage(Message):
def __init__(self, text, shift):
'''
Initializes a PlaintextMessage object
Initializes a PlaintextMessage object

text (string): the message's text
shift (integer): the shift associated with this message

Expand All @@ -135,90 +162,130 @@ def __init__(self, text, shift):
self.message_text_encrypted (string, created using shift)

'''
pass #delete this line and replace with your code here
self.message_text = text
self.valid_words = load_words(WORDLIST_FILENAME)
self.shift = shift
self.encryption_dict = self.build_shift_dict(shift)
self.message_text_encrypted = self.apply_shift(shift)
# pass #delete this line and replace with your code here

def get_shift(self):
'''
Used to safely access self.shift outside of the class

Returns: self.shift
'''
pass #delete this line and replace with your code here
return self.shift
# pass #delete this line and replace with your code here

def get_encryption_dict(self):
'''
Used to safely access a copy self.encryption_dict outside of the class

Returns: a COPY of self.encryption_dict
'''
pass #delete this line and replace with your code here
return self.encryption_dict.copy()
# pass #delete this line and replace with your code here

def get_message_text_encrypted(self):
'''
Used to safely access self.message_text_encrypted outside of the class

Returns: self.message_text_encrypted
'''
pass #delete this line and replace with your code here
return self.message_text_encrypted
# pass #delete this line and replace with your code here

def change_shift(self, shift):
'''
Changes self.shift of the PlaintextMessage and updates other
attributes determined by shift.
Changes self.shift of the PlaintextMessage and updates other
attributes determined by shift.

shift (integer): the new shift that should be associated with this message.
0 <= shift < 26

Returns: nothing
'''
pass #delete this line and replace with your code here
self.shift = shift
self.encryption_dict = self.build_shift_dict(shift)
self.message_text_encrypted = self.apply_shift(shift)
# pass #delete this line and replace with your code here


class CiphertextMessage(Message):
def __init__(self, text):
'''
Initializes a CiphertextMessage object

text (string): the message's text

a CiphertextMessage object has two attributes:
self.message_text (string, determined by input text)
self.valid_words (list, determined using helper function load_words)
'''
pass #delete this line and replace with your code here
self.message_text = text
self.valid_words = load_words(WORDLIST_FILENAME)
# pass #delete this line and replace with your code here

def apply_shift_down(self, shift, msg):
alphabet = "abcdefghijklmnopqrstuvwxyz"
d1 = {ch: alphabet[i - shift] for i, ch in enumerate(alphabet)}
alphabet = alphabet.upper()
d2 = {ch: alphabet[i - shift] for i, ch in enumerate(alphabet)}
d = {**d1, **d2}
l = []
for ch in msg:
if ch in d.keys():
l.append(d[ch])
else:
l.append(ch)
return "".join(l)

def decrypt_message(self):
'''
Decrypt self.message_text by trying every possible shift value
and find the "best" one. We will define "best" as the shift that
creates the maximum number of real words when we use apply_shift(shift)
on the message text. If s is the original shift value used to encrypt
the message, then we would expect 26 - s to be the best shift value
the message, then we would expect 26 - s to be the best shift value
for decrypting it.

Note: if multiple shifts are equally good such that they all create
the maximum number of valid words, you may choose any of those shifts
Note: if multiple shifts are equally good such that they all create
the maximum number of valid words, you may choose any of those shifts
(and their corresponding decrypted messages) to return

Returns: a tuple of the best shift value used to decrypt the message
and the decrypted message text using that shift value
'''
pass #delete this line and replace with your code here
count = [0] * 27
for k in range(0, 27):
for word in self.get_message_text().split(" "):
if is_word(self.get_valid_words(), self.apply_shift_down(k, word)):
count[k] += 1
return self.apply_shift_down(count.index(max(count)), self.get_message_text())

# pass #delete this line and replace with your code here


if __name__ == '__main__':
# #Example test case (PlaintextMessage)
# plaintext = PlaintextMessage('hello', 2)
# print('Expected Output: jgnnq')
# print('Actual Output:', plaintext.get_message_text_encrypted())
#
# #Example test case (CiphertextMessage)
# ciphertext = CiphertextMessage('jgnnq')
# print('Expected Output:', (24, 'hello'))
# print('Actual Output:', ciphertext.decrypt_message())

# TODO: WRITE YOUR TEST CASES HERE

# TODO: best shift value and unencrypted story
msg = load_words("story.txt")
ciphertext = CiphertextMessage(" ".join(msg))
print(ciphertext.decrypt_message())
# pass #delete this line and replace with your code here




# #Example test case (PlaintextMessage)
# plaintext = PlaintextMessage('hello', 2)
# print('Expected Output: jgnnq')
# print('Actual Output:', plaintext.get_message_text_encrypted())
#
# #Example test case (CiphertextMessage)
# ciphertext = CiphertextMessage('jgnnq')
# print('Expected Output:', (24, 'hello'))
# print('Actual Output:', ciphertext.decrypt_message())

#TODO: WRITE YOUR TEST CASES HERE

#TODO: best shift value and unencrypted story

pass #delete this line and replace with your code here
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