How to generate random characters within an existing string?

Question

I'm making a text converter, and I'd like to select random characters in a string that already exists.

When I research it, all that comes up is someone that wants to generate random letters in the alphabet or someone that wants to generate a random string. That's not what I'm looking for.

new_string = ""
index = 0

for letter in input_text:
    if letter not in "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM":
        new_string = new_string + (letter)
        continue
    index += 1
    if index % 2 == 0:
        new_string = new_string + (letter.upper())
    else:
        new_string = new_string + (letter.lower())

My existing text converter capitalizes every other letter, but I'd like to have it randomly capitalize the letters. Is this possible?

Instead of checking whether the index is even or odd, you could check if a [random integer](https://docs.python.org/3/library/random.html#random.randint) is 0 or 1. — Stephen B, Jul 02 '19 at 18:41
You should consider editing the question to fix the indentation and make the title reflect what you're actually asking. It doesn't seem like you're asking how to generate random characters. — Mark, Jul 02 '19 at 18:43

j6m8 · Answer 1 · 2019-07-02T18:50:16.963

You may want to look at the random.choice and random.choices functions in the random library (built-in), which allows you to randomly select an item from a list:

>>> import random
>>> a = random.choice("ABCDabcd")
'C'
>>> my_text = "".join(random.choices("ABCDabcd", k=10))
'baDdbAdDDb'

In order to randomly capitalize, you can choice from a list of the lower- and upper-case version of a letter:

import random

new_string = ""
for letter in input_text:
    if letter not in "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM":
        new_string = new_string + (letter)
    else:
        new_string += random.choice([letter.upper(), letter.lower()])

(Note that random.choices returns a list, not a str, so we need to join() the elements together.)

Finally, you may also want to use the isalpha function:

>>> "A".isalpha()
True
>>> "a".isalpha()
True
>>> "7".isalpha()
False

(Relevant question)

But upper() and lower() functions have no effect on non-alpha characters. So you can completely remove this check from your code:

new_string = ""
for letter in input_text:
    new_string += random.choice([letter.upper(), letter.lower()])

Despite the title, this isn't what the question is actually asking. — Mark, Jul 02 '19 at 18:44

How to generate random characters within an existing string?

1 Answers1