3) e. Tuples
From the first glance tuples might seem very similar to lists.
- Like lists tuples are ordered sets.
- Unlike lists tuples are immutable (can’t be changed).
That means that after you create a tuple you can only read its value and if you need to change it you will need to create a new one.
Because of that there is no reason to create an empty tuple if you want to populate it later. Instead you will have to declare a tuple literally by using parenthesis or use the tuple function to convert another iterable into a tuple.
So what can you do with a data structure that cannot be changed?
Similarly to lists you access tuple’s elements by their position.
1 2 | Output: Bob |
If you try to change an element in a tuple then you will get an error. However, you can reassign all values to the tuple instead. That doesn’t really change the existing tuple but merely creates a new one with the same name. Here is an example to illustrate this:
1 2 | Output: (1, 3, 4, 5) |
Methods:
index(e): Return the position of the first occurrence of e in tuple.
1 2 | Output: 2 |
count(e): Return number of occurrences of e in tuple.
1 2 | Output: 3 |
So yeah, there’s not a lot you can do with tuples. But that can be a good thing too.
Tuples are commonly used when a function needs to return multiple values.
1 2 3 4 5 6 7 8 | def get_example_student(): return ("Ray", "Morrison", 20) student = get_example_student() first_name = student[0] last_name = student[1] age = student[2] |
In fact this kind of pattern is so common that Python allows us to simplify the syntax.
Isn’t that much simpler?