How would you make a comma-separated string from a list of strings?

Question

What would be your preferred way to concatenate strings from a sequence such that between every two consecutive pairs a comma is added. That is, how do you map, for instance

Answer 1

My two cents. I like simpler an one-line code in python:

>>> from itertools import imap, ifilter
>>> l = ['a', '', 'b', 1, None]
>>> ','.join(imap(str, ifilter(lambda x: x, l)))
a,b,1
>>> m = ['a', '', None]
>>> ','.join(imap(str, ifilter(lambda x: x, m)))
'a'

It's pythonic, works for strings, numbers, None and empty string. It's short and satisfies the requirements. If the list is not going to contain numbers, we can use this simpler variation:

>>> ','.join(ifilter(lambda x: x, l))

Also this solution doesn't create a new list, but uses an iterator, like @Peter Hoffmann pointed (thanks).