Sort a sublist of elements in a list leaving the rest in place

Question

Say I have a sorted list of strings as in:

[\'A\', \'B\' , \'B1\', \'B11\', \'B2\', \'B21\', \'B22\', \'C\', \'C1\', \'C11\', \'C2\']

Now I wan

Answer 1

Most of the answers focused on the B's while I needed a more general solution as noted. Here's one:

def _order_by_number(items):
    regex = re.compile(u'(.*?)(\d*)$') # pass a regex in for generality
    keys = {k: regex.match(k) for k in items}
    keys = {k: (v.groups()[0], int(v.groups()[1] or 0)) 
            for k, v in keys.iteritems()}
    items.sort(key=keys.__getitem__)

I am still looking for a magic key however that would leave stuff in place