How to convert string to Title Case in Python?

This one would always start with lowercase, and also strip non alphanumeric characters:

def camelCase(st):
    output = ''.join(x for x in st.title() if x.isalnum())
    return output[0].lower() + output[1:]

Why not use title Right from the docs:

>>> "they're bill's friends from the UK".title()
"They'Re Bill'S Friends From The Uk"

If you really wanted PascalCase you can use this:

>>> ''.join(x for x in 'make IT pascal CaSe'.title() if not x.isspace())
'MakeItPascalCase'

def capitalizeWords(s):
  return re.sub(r'\w+', lambda m:m.group(0).capitalize(), s)

re.sub can take a function for the "replacement" (rather than just a string, which is the usage most people seem to be familiar with). This repl function will be called with an re.Match object for each match of the pattern, and the result (which should be a string) will be used as a replacement for that match.

A longer version of the same thing:

WORD_RE = re.compile(r'\w+')

def capitalizeMatch(m):
  return m.group(0).capitalize()

def capitalizeWords(s):
  return WORD_RE.sub(capitalizeMatch, s)

This pre-compiles the pattern (generally considered good form) and uses a named function instead of a lambda.