Python list, .replace() problems

Question

sentence = input("Say a sentence: ").split()
vowels = 'aeiouAEIOU'                       
for i in sentence:
    if i.isalpha() == True:
        if i[0] in vowels:
            print(i + "way")
            new = i + "way"
            sentence.replace(i, new)
        else:
            print(i[1:] + i[0] + "ay")
            new = i[1:] + i[0] + "ay"
            sentence.replace(i, new)
    else:
        print(i)
print(sentence)

I am trying to make a piglatin sentence converter, I have been able to make the converter print the correct values for the translation, but I cannot make the program change the actual values of the list, which I need it to do so that I can print the converted text like the original, in a string format like "I like rabbits" instead of a list like:

I
like
rabbits

I would like to know how I use the replace() function to change my list inside my for loop and if statements. If there is another way that is better that would be even better. Thank You.

Maciej Gol · Accepted Answer · 2013-12-02 21:04:08Z

2

sentence.replace(i, new) function returns the new string - it doesn't do replacement in-place (on the original string).

You'd want to loop through indexes to easily modify the list being iterated over (you don't change your wheels whilst driving, do you?):

sentence = input("Say a sentence: ").split()
vowels = 'aeiouAEIOU'                       
for idx in range(len(sentence)):
    to_replace = sentence[idx]
    if to_replace.isalpha() == True:
        if to_replace[0] in vowels:
            print(to_replace + "way")
            new = i + "way"
        else:
            print(to_replace[1:] + to_replace[0] + "ay")
            new = to_replace[1:] + to_replace[0] + "ay"
        sentence[idx] = new
    else:
        print(to_replace)
print(sentence)

You don't really need to call replace() (which is a string method, not list). You'd assign to sentence[idx] instead.

edited Dec 2, 2013 at 21:04

answered Dec 2, 2013 at 20:58

Maciej Gol

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4 Comments

Floofk Over a year ago

I have tried this and I does not output anything, I have changed it to put everything in a function, so sentence is now x, but it doesn't output anything on my screen.

Floofk Over a year ago

pastebin.com/F9nc6Dpy I think the range() does not work in python 3 I read something about it on codecademy, I think it is a generator now, the same as xrange in 2.7

Maciej Gol Over a year ago

@user3058928, the function you have made out of the snippet is wrong, here is the fixed one pastebin.com/mBK6QHKC.

Floofk Over a year ago

Cheers for the help :D

tijko · Accepted Answer · 2013-12-02 21:25:03Z

0

Your list doesn't have a .replace method but, the str's in the list do.

It looks as though you are wanting to modify your list while iterating through the items.

sentence = input("Say a sentence: ").split()
vowels = 'aeiouAEIOU'                       
for idx, word in enumerate(sentence):
    if word.isalpha() == True:
        if word[0] in vowels:
            print(word + "way")
            new = word + "way"
        else:
            print(word[1:] + word[0] + "ay")
            new = word[1:] + word[0] + "ay"
        sentence[idx] = new
    else:
        print(word)
print(sentence)

The enumerate builtin is especially useful when iterating and modifying items.

answered Dec 2, 2013 at 21:25

tijko

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