What’s a Tuple?

  • A tuple is a type of sequence that resembles a list, except that, unlike a list, a tuple is immutable (it’s structure can’t change).

How Can I Define a Tuple?

  • A tuple looks just like a list except you use parentheses instead of square brackets.
    • Once defined, you can access individual elements by using each item’s index, just as you would for a list.
  • Example: If we have two colors that should always remain the same, we can ensure that the colors don’t change by putting the colors into a tuple:
python
1colors = ('purple','gold')
2
3print(colors[0])
4print(colors[1])

Output:

1purple
2gold
  • Note what happens if we try to change one item in the list:
python
1colors = ('purple','gold')
2
3colors[0] = "violet"
4
5print(colors[0])
6print(colors[1])

Output:

1colors[0] = "violet"
2TypeError: 'tuple' object does not support item assignment

Tuples are Practical!

  • They are used to group together related data, such as a person’s name, their birthdate and their gender.
  • Tuple arrays can themselves be other tuples. For example, we could improve the information about a certain object, such as a student, to hold not only his/her name but other attributes as well.
    • Example:
python
1nationalParks = (("Great Smoky Mountains", "NC"),
2                ("Arches", "UT"),
3                ("Yosemite","CA"))
4
5print(nationalParks[1])

Output:

1('Arches', 'UT')