Capitalize the first letter of each word in a string in Python

Question

Having a slight problem with this function in Python that's supposed to return the first letter of every word in a string capitalized and everything else lowercased:

def titleize(phrase):
    split_phrase = phrase.split()

    for word in split_phrase:
        word.capitalize()

    return ' '.join(split_phrase)

titleize('oNLy cAPITALIZe fIRSt') -> oNLy cAPITALIZe fIRSt

Clearly the issue is with the loop over the phrase (I think) that is being split and I suspect it's not mutating but rather creating something new but I'm stuck trying to fix it.

The issue here is that you aren't saving it when you do `word.capitalize()` so still `split_phrase` has not been updated, but see below of how to use the built-in `str.title` function — astrochun, Feb 21 '21 at 06:05

score 12 · Answer 1 · 2021-02-21T06:25:34.927

12

Might I suggest the use of the built-in str.title() function?

def titleize(phrase):
    capitalize_first = phrase.title()
    return capitalize_first
    
print(titleize('oNLy cAPITALIZe fIRSt'))

Output:

Only Capitalize First

edited Feb 21 '21 at 06:25

answered Feb 21 '21 at 06:02

costaparas · Answer 2 · 2021-02-21T06:17:57.093

You aren't assigning the result anywhere -- the split_phrase variable doesn't change at any point.

You could use str.title() as suggested by @pythonenthusiast, or use a list comprehension to simplify your current approach:

def titleize(phrase):
    return ' '.join([word.capitalize() for word in phrase.split()])

The corrected version of your original code could look like this:

def titleize(phrase):
    split_phrase = phrase.split()
    result = []
    for word in split_phrase:
        result.append(word.capitalize())
    return ' '.join(result)

Here, a new result list is created, and in each iteration, we append the changed word to the list. At the end, we join and return the new result list.

Capitalize the first letter of each word in a string in Python

2 Answers2