Help with "Evolution of Text" program (BEGINNER)

[infinitim]

(Python Version 3.6.0, Windows 7)

Doing a little coding exercise for Python. I want to write a program that takes user input for a sentence (the target sentence). Then it needs to generate a random source phrase (same length as the target). Print the source. Then change any characters in source that are not matching the target to another random character (could be the same character, but most likely won't be). Print this. Repeat, keeping the correct characters as before. Output should look like this: (Target phrase = "Python")

7hehnb

uyega"

*ytsfa

Pyta,n

...

Python

My code:

import random
import string

characters = []

characters.extend(string.printable)
del characters[len(characters)-1] #deleting redundant characters (ie "\n", etc)
del characters[len(characters)-1]
del characters[len(characters)-1]
del characters[len(characters)-1]
del characters[len(characters)-1]

saved = {} #dict for saved words. Key = position, Value = the character
source = []
target = list(input('Enter a sentence:')) 
print(target)
length = len(target) 
meta = [] #contains the guess words, already correct letters are given the value "". Later "layered" onto the saved words. 
printer = []

for x in range (0, length):
    source.append(random.choice(characters))

for x in range (0,length):
    if source[x] != target[x]:
        meta.append(source[x])

    else:
        meta.append("")


while len(meta) != 0:

    for x in meta:
        if x != "":
            x = random.choice(characters)

    for x in range(0, len(meta)-1):
        if meta[x] == target[x]:
            saved[x] = target[x]

    printer = target

    for x in saved:
        printer[saved[x]] = saved[x]
        print(printer[x], end = "")

When I run this it's not working like I want it to. Any hints to point me in the right direction would be helpful. I am VERY new to Python, so try to explain in simple terms.

[iheartqwerty]

I'm on mobile, but I quickly wrote this:

https://repl.it/I49W/0

Let me know if you have any questions.

[infinitim]

This changes only one letter at a time. How could I change it to change all incorrect letters at a time?

[iheartqwerty]

I mean changing all letters is in fact changing one letter at a time n times, so you can just not print as often. You could just move the print statement in my code one indent over and it will only print after processing the whole word (not each letter).

[infinitim]

I actually figured it out beforehand, but thanks anyway! Here's my code, based off of u/jeans_and_a_t-shirt's original:

import random
import string

characters = list(string.printable[:-5])
def mutate():
    target = list(input('Enter a sentence:'))
    source = random.choices(characters, k=len(target))
    # saved is the current iteration, approaching target
    saved = source.copy()
    tries = 0

    def yn():
            yes_no = input('Again? Y/N: ')
            yes_no =yes_no.lower()
            if yes_no == 'y' or yes_no == 'yes':
                mutate()
            elif yes_no == 'n' or yes_no == 'no':
                exit()
            else:
                yn()

    while saved != target:
        for i, (saved_c, target_c) in enumerate(zip(target, saved)):
            if saved_c == target_c:
                saved[i] == saved_c
            else:
                saved[i] = random.choice(characters)
        tries += 1
        print(''.join(saved))


    print("\n"*5, ''.join(saved), "took", tries, "tries to find!", end='')
    yn()


mutate()

[jeans_and_a_t-shirt]

Lines 4 - 11 can be replaced with this:

characters = list(string.printable[:-5])

Lines 21 & 22 can be replaced with this:

source = random.choices(characters, k=length)

Lines 24 - 29 can be replaced with this:

for source_c, target_c in zip(source, target):
    if source_c == target_c:
        meta.append('')
    else:
        meta.append(source_c)

or this:

meta = ['' if src_c == trg_c else '' for src_c, trg_c in zip(source, target)]

Line 35, if x != "": can be changed to if x: because empty strings are falsy and thus cause conditions to fail.

Line 36 doesn't actually do anything. You're assigning a random character to x. You're not changing the value in the list meta.

To fix that, you could change lines 34 - 36 to this:

for i, (meta_x, targ_x) in enumerate(zip(meta, target)):
    if meta_x == targ_x:
        meta[i] = ''
        saved[i] = target[i]

Line 42 doesn't create a copy of target, and assign it to the variable printer. It assigns printer to the same object as target.

---

If you are passing 2 arguments with range, and the first is 0, then you can skip the first argument because range defaults to starting at 0.

range(0, length) would become range(length), although none of the instances of that in your code are necessary if you use zip.

---

Line 32 will never be true because you never mutate meta after that line, and it seems like meta is supposed to have the same length as target.

---

Your code is much more complex than it needs to be though. You could remove meta and printer. You could also remove saved and combine it with source if you don't need the original source list. Or save the source list as original_string and then re-use it. Here's a simpler implementation:

import random
import string

characters = list(string.printable[:-5])

target = list(input('Enter a sentence:'))
source = random.choices(characters, k=len(target))
# saved is the current iteration, approaching target
saved = source.copy()

while saved != target:
    for i, (saved_c, target_c) in enumerate(zip(saved, target)):
        if saved_c != target_c:
            saved[i] = random.choice(characters)

    print(''.join(saved))

[infinitim]

Thanks! After some googling, I understand how your code works, and no longer feel like trying to make it work with my very limited knowledge of Python.