# [Tutor] Sets

**Norvell Spearman
**
norvell@houseofspearman.org

*Fri Apr 18 03:58:02 2003*

On Thursday, 2003.04.17, 19:23:47 -0700, Sean 'Shaleh' Perry wrote:
>* On Thursday 17 April 2003 17:32, Brian Christopher Robinson wrote:
*>* > I think I read that sets will be a primitive data type in the next version
*>* > of Python, but what is a good way to implement them now?
*>*
*>* use a dictionary.
*
Not that I know a better implementation (I'm new to Python and only
recently began studying set theory), but why is using a dictionary a
good way to implement sets? According to the set theory text I'm using
(and this is the text's notation, not Python code):
(1) {a, a} = {a}
(2) {a, b} = {b, a}
Since dictionaries are unordered (2) above is covered, but wouldn't (1)
(if one creates a set class using a dictionary) require a method to get
rid of---or ignore---duplicates? Or would one implement a set where the
dictionary's key:value pairs are item:frequency and two sets are equal
if their respective dictionaries contain the same items, ignoring
frequencies > 0? Would the null set then be represented by
my_set = {}
Or am I using ``sets'' in the wrong context?
Thanks for any answers.
--
Norvell Spearman