CODEWITHSUNDEEP
pythonlist
Bennet
Bennet

Reputation: 5

How to check if a value exists in a list, and store the elements that include it in variables

I'm trying to make an encrypter, where it shifts the letter 3 times (so A becomes D, B becomes E, etc.) Then X goes back to A, Y to B, and Z to C. I'm using ASCII values to shift them. I'm trying to see if any part of the list has the ASCII values of X, Y, or Z, then if yes, change that element back to A, B, or C's ASCII value. I know you can check if there is a value in a list, but how do I actually take this value and change it? Here is what I'm trying to do:

def encrypt(userInput):
    #Find Ascii Value of plaintext
    asciiValue = [ord(c) for c in userInput]
    #Convert Ascii value (list) into integers
    intAscii = [int(x) for x in asciiValue]

    encryptedAscii = [n + 3 for n in intAscii]
    if '120' in encryptedAscii:
        encryptedAscii = '97'
    elif '121' in encryptedAscii:
        encryptedAscii = '98'
    elif '122' in encryptedAscii:
        encryptedAscii = '99'
    else:
        encryptedOutput = ''.join(chr(v) for v in encryptedAscii)
    return encryptedOutput

Thanks!

Upvotes: 0

Views: 64

Answers (2)

Patrick Artner
Patrick Artner

Reputation: 51683

Using ord and chr is fine, but there is also an easier method: str.maketrans and str.translate:

from string import ascii_uppercase as ABC, ascii_lowercase as abc

def encrypt(text, tr):
    return text.translate(tr)

# join translation dicts for ABCD and abcs to 
# create mapping from 2 strings of equal lenght, 
# first is "from" second is "to" mapping:  
tr = {**str.maketrans(abc, abc[3:]+abc[:3]),     # lower case a-z
      **str.maketrans(ABC, ABC[3:]+ABC[:3])}     # upper case A-Z

text = "ABCDEFGXYZabcdefgxyz"
print(text, " => ", encrypt(text,tr))

Output:

ABCDEFGXYZabcdefgxyz  =>  DEFGHIJABCdefghijabc

Upvotes: 0

sahinakkaya
sahinakkaya

Reputation: 6056

You actually don't need to check for x, y, z separately. Just use the modulo operator (%) so if it overflows, it will turn back to a, b, c:

def encrypt(userInput):
    # Find Ascii Value of plaintext
    asciiValue = [ord(c) for c in userInput]
    # Convert Ascii value (list) into integers
    intAscii = [int(x) - 97 for x in asciiValue]

    encryptedAscii = [(n + 3) % 26 + 97 for n in intAscii]
    encryptedOutput = ''.join(chr(v) for v in encryptedAscii)
    return encryptedOutput

from string import ascii_lowercase
print(encrypt(ascii_lowercase))

Output:

defghijklmnopqrstuvwxyabc

Upvotes: 1

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