Python: add a number of random letters (A-Z; a-z) after each letter in a given word?

Question

I need to write a program that will add a number of random letters after each letter in the supplied word.

Here is what I have:

import random
import string

def add_letters(word,number):

    for i in range(number):
        letters=''.join(random.choice(string.ascii_letters))         
        new_word=(letters.join(word))
    return new_word

Here is what the output is supposed to look like if we enter add_letters(cat,1):

cZaQtR

My program always returns 1 letter even if I give it a different number. Also, it's always the same "random" letter after each letter in the word.

Any idea what I'm doing wrong?

Answer 1

Your logic is not correct. I would suggest adding some debugging printout inside your loop and see what you get, something like the following:

for i in range(number):
    letters=''.join(random.choice(string.ascii_letters))         
    new_word=(letters.join(word))
    print i, letters, word, new_word

This should tell you where you are going wrong. As an extra hint, you might use a second loop outside the first one.

Answer 2

There are a lot of logic errors here, and some clumsy coding (but don't worry, you'll get better while practicing)

• At each loop, your new_word gets erased
• You are assigning to new_word a generated letter plus the original word, it's not what you want to do.
• No need to use ''.join

A correct answer would be something like:

def add_letters(word,number):
    new_word = ""
    for c in word: # iterate through the word
        letters = ""
        for k in range(number): # concatenate n random letters
            letters += random.choice(string.ascii_letters)   
        new_word += c + letters # add the current char plus the letters to the new word
return new_word

Answer 3

You're never maintaining your added letters on each iteration.

You do new_word=(letters.join(word)) on every iteration, which will never keep the random letters from previous iterations, and using 'something'.join('another something') will add the 'something' in between every character of the 'another something'.

What you would want to look at instead, would be something more along the lines of

def add_letters(word, number):
    new_word = ''

    for character in word:
        new_word += character
        for _ in range(number):
            new_word += random.choice(string.ascii_letters)

    return new_word

which will iterate over every character of the supplied word, add it to the new_word string, then randomly choose as many characters as required and add them to the new_word , and continue till the original word is finished, and returns the new word.

Answer 4

Your problem is happening when you enter your loop you are always only generating at most one random character at a time with this:

letters=''.join(random.choice(string.ascii_letters))

You might want to look at your problem a different way, and instead, make use of another method in random called sample

With sample, you can provide how many random characters you want every time you call it, and they will be unique. This in effect changes your loop to instead of iterating over your number , to iterate over the word and add your characters accordingly.

import random
import string

def add_letters(word,number):
    new_word = ""
    for i in word:
        letters = ''.join(random.sample(string.ascii_letters, number))
        new_word += "{}{}".format(i, letters)
    return new_word

Calling:

add_letters('cat', 2)

Outputs:

cNbarHtTM

Answer 5

import random
import string

def add_letters(word,number):
    """
    Adds "number" randomly selected ASCII letters to the end of "word"
    """

    return word + "".join([random.choice(string.ascii_letters) for k in range(number)])


for i in range(10):
    print(add_letters("foo", i))

The [random.choice...] thing is a list comprehension. They're a really cool, powerful thing in Python, which I'd recommend you read up on if you don't fully understand the code.

Answer 6

As Conor said, the logic is off. Try and break apart the problem statement and see if you can find a solution to each. "add a number of random letters" - can you create this string?

after "each letter in the supplied word." can you split apart the word into separate letters?