Question

I’d like to convert a string of text, e.g., “User Name” into something which I can turn into part of a url, e.g., “User-Name.” What’s the fastest way to do a string replacement (“-” for ” “) as well as make sure that characters are only [a-zA-Z0-9]?

Answer 1

string.translate is often the fastest solution for these sorts of problems (assuming your strings aren’t unicode).

def translate(x):
    if x == ' ': return '-'
    if 'a' <= x <= 'z': return x
    if 'A' <= x <= 'Z': return x
    if '0' <= x <= '9': return x

def mk_translator():
    translations = ''.join(translate(chr(c)) or chr(c) for c in xrange(256))
    deletions = ''.join(chr(c) for c in xrange(256) if translate(chr(c)) is None)
    return translations, deletions

def urlize(x, translator=mk_translator()):
    return x.translate(*translator)

print urlize('User Name')