Java's TreeSet equivalent in Python?

Question

I recently came across some Java code that simply put some strings into a Java TreeSet, implemented a distance based comparator for it, and then made its merry way into the

Answer 1

I'd need to see some example data, but if you're just trying to do a weighted sort, then the builtin python sorted() can do it, two ways.

With well ordered tuples and a key() function:

def cost_per_page(book):
    title, pagecount, cost = book
    return float(cost)/pagecount

booklist = [
        ("Grey's Anatomy", 3000, 200),
        ('The Hobbit', 300, 7.25),
        ('Moby Dick', 4000, 4.75),
]
for book in sorted(booklist, key=cost_per_page):
    print book

or with a class with a __cmp__ operator.

class Book(object):
    def __init__(self, title, pagecount, cost):
        self.title = title
        self.pagecount = pagecount
        self.cost = cost
    def pagecost(self):
        return float(self.cost)/self.pagecount
    def __cmp__(self, other):
        'only comparable with other books'
        return cmp(self.pagecost(), other.pagecost())
    def __str__(self):
        return str((self.title, self.pagecount, self.cost))

booklist = [
        Book("Grey's Anatomy", 3000, 200),
        Book('The Hobbit', 300, 7.25),
        Book('Moby Dick', 4000, 4.75),
]
for book in sorted(booklist):
    print book

Both of these return the same output:

('Moby Dick', 4000, 4.75)
('The Hobbit', 300, 7.25)
("Grey's Anatomy", 3000, 200)