Sets and tuples

Sets are similar to lists in that they contain a list of elements, though they must be unique items. With this, the elements must be immutable, meaning that the value must remain constant. For this, sets are best used on integers, strings, Boolean, floats, and tuples as elements. Sets do not index the elements, and therefore we cannot access the elements by their location in the set. Instead, we can access and remove elements through the use of the pop() method mentioned for the list method. Tuples are also similar to lists, though they are immutable. Built using parenthesis in lieu of brackets, elements do not have to be unique and of any data type:

>>> type(set([1, 4, 'asd', True]))
<class 'set'>
>>> g = set(["element1", "element2"])
>>> g
{'element1', 'element2'}
>>> g.pop()
'element2'
>>> g
{'element1'}
>>> tuple('foo')
('f', 'o' , 'o')
>>> ('b', 'a', 'r')
('b', 'a', 'r')
>>> ('Chapter1', 22)[0]
Chapter1
>>> ('Foo', 'Bar')[-1]
Bar 

The important difference between a tuple and a list is that a tuple is immutable. This means that we cannot change a tuple object. Instead, we must replace the object completely or cast it to a list, which is mutable. This casting process is described in the next section. Replacing an object is very slow since the operation to add a value to a tuple is tuple = tuple + ('New value',), noting that the trailing comma is required to denote that this addition is a tuple.