Python: how to join entries in a set into one stri

Question

Basically, I am trying to join together the entries in a set in order to output one string. I am trying to use syntax similar to the join function for lists. Here is my attempt:

list = ["gathi-109","itcg-0932","mx1-35316"]
set_1 = set(list)
set_2 = set(["mx1-35316"])
set_3 = set_1 - set_2
print set_3.join(", ")

However I get this error: AttributeError: 'set' object has no attribute 'join'

What is the equivalent call for sets?

Answer 1

Nor the set nor the list has such method join, string has it:

','.join(set(['a','b','c']))

By the way you should not use name list for your variables. Give it a list_, my_list or some other name because list is very often used python function.

Answer 2

Set's do not have an order - so you may lose your order when you convert your list into a set, i.e.:

>>> orderedVars = ['0', '1', '2', '3']
>>> setVars = set(orderedVars)
>>> print setVars
('4', '2', '3', '1')

Generally the order will remain, but for large sets it almost certainly won't.

Finally, just incase people are wondering, you don't need a ', ' in the join.

Just: ''.join(set)

:)