Think Python, 3rd Edition

Chapter 11. Tuples

This chapter introduces one more built-in type, the tuple, and then shows how lists, dictionaries, and tuples work together. It also presents tuple assignment and a useful feature for functions with variable-length argument lists: the packing and unpacking operators.

In the exercises, we’ll use tuples, along with lists and dictionaries, to solve more word puzzles and implement efficient algorithms.

One note: there are two ways to pronounce “tuple.” Some people say “tuh-ple,” which rhymes with “supple.” But in the context of programming, most people say “too-ple,” which rhymes with “quadruple.”

Tuples Are Like Lists

A tuple is a sequence of values. The values can be any type, and they are indexed by integers, so tuples are a lot like lists. The important difference is that tuples are immutable.

To create a tuple, you can write a comma-separated list of values:

t = 'l', 'u', 'p', 'i', 'n'
type(t)
       

tuple
       

Although it is not necessary, it is common to enclose tuples in parentheses:

t = ('l', 'u', 'p', 'i', 'n')
type(t)
       

tuple
       

To create a tuple with a single element, you have to include a final comma:

t1 = 'p',
type(t1)
       

tuple
       

A single value in parentheses is not a tuple:

t2 = ('p')
type(t2)
       

str
       

Another way to create a tuple is the built-in function tuple. With no argument, it creates an empty tuple:

t = tuple()
t
       

()
       

If the argument is a sequence (string, list, or tuple), the result is a tuple with the elements of the sequence:

t = tuple('lupin' ...