Python Title Case, but leave pre-existing uppercase

Question

I'm looking for a very pythonic way (Python 3.x) of doing the following, but haven't come up with one yet. If I have the following string:

string = 'this is a test string'

I can title case it with:

string.title()

Which results in:

'This Is A Test String'

However, I want to convert if I have the following string:

string = 'Born in the USA'

Applying the title case results in:

string = 'Born In The Usa'

Should results in:

'Born In The USA'

I am looking for a way to do a title case, but not adjust existing upper case text. Is there any way to do this?

Answer 1

It is unclear what output you are expecting.

If you wanted to ignore the whole string because it contains uppercased words, test if the string is lowercase first:

if string.islower():
    string = string.title()

If you wanted to only ignore specific words that already have uppercase letters, split the string on whitespace, and titlecase only those that are lowercase:

string = ' '.join([w.title() if w.islower() else w for w in string.split()])

Demo of the latter approach:

>>> string = 'Born in the USA'
>>> ' '.join([w.title() if w.islower() else w for w in string.split()])
'Born In The USA'

Answer 2

What about:

string = 'born in the USA'

title = "".join([a if a.isupper() else b for a,b in zip(string,string.title())])
print title

Displaying:

Born In The USA

Not very efficient, but will preserve uppercases in the original string, yet allowing to capitalize other words.