How do I unstring in python

Question

So I am trying to make a text encryptionish program that will change the letters in text to a different ordred alphabet, however a = key[1](Key being the name of the rearanged alphabet) but it dosn't work because key[1] can't be assigned to a litteral, any ideas of how to get arround this.

Answer 1

So key is your rearranged alphabet, and ALPHA is the normal alphabet.

ALPHA = 'abcdefghijklmnopqrstuvwxyz'
key = 'zwlsqpugxackmirnhfdvbjoeyt'
msg = 'secretmessage'
code = []

for i in msg:
    code.append(key[ALPHA.index(i)])

print(''.join(code))

Make the string after encoding, rather than during encoding.

Answer 2

Strings in Python, and many other languages, are immutable, because reasons.

What you need is to create a new string, replacing characters as needed.

For byte strings (that in Python are plain byte arrays) there's .translate. It takes a 256-byte string that describes how to replace each possible byte.

For Unicode strings .translate takes a map which is a bit more convenient but still maybe cumbersome:

unicode('foo bar').translate({ord('f'): u'F', ord('b'): u'B'})

In general case, something like this should work:

def transform_char(char):
  # shift a characte 3 positions forward
  return chr(ord(char) + 3)

def transform(source_string):
  return ''.join(transform_char(c) for c in source_string)

What happens in transform? It generates a list of transformed characters ([transform_char(c) for c in source_string]) is called a "list comprehension". This list contains a transformed character for each character in source_string. Then all elements of this list are efficiently joined together by placing an empty string '' between them.

I hope it's enough for you now.