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Tuples

Lists and dictionaries work well for storing and manipulating data during the execution of a program. Both lists and dictionaries are mutable. However, sometimes you’ll want to create a collection of elements that are immutable (can't change). Tuples allow you to do just that.

# coordinates of MCI IV
coordinates = (47.262996862335854, 11.393082185178823)
print(type(coordinates))
>>> Output
<class 'tuple'>

A tuple is created with round brackets (()). As with lists and dictionaries, the elements are separated by commas. Tuples can hold any type of data.

Accessing elements

With indexing, the individual elements of a tuple can be retrieved.

coordinates = (47.262996862335854, 11.393082185178823)
print(coordinates[0])
print(coordinates[1])
>>> Output
47.262996862335854
11.39308218517882

Immutability

Let's try to change the value of an element in a tuple.

coordinates = (47.262996862335854, 11.393082185178823)
coordinates[0] = 50.102

we will encounter following error:

Traceback (most recent call last):
  File "<ipython-input-29-d74dc80ea879>", line 2, in <module>
    coordinates[0] = 50.102
    ~~~~~~~~~~~^^^
TypeError: 'tuple' object does not support item assignment

As a tuple is immutable, you can only redefine the entire tuple.

coordinates = (47.262996862335854, 11.393082185178823)
# redefine the entire tuple
coordinates = (5.513615392318705, 95.2060492604128)

tuple unpacking

Tuples can be unpacked, to use them separately.

coordinates = (47.262996862335854, 11.393082185178823)
latitude, longitude = coordinates
Info

Tuples are often used for constants. In the above examples, we used coordinates. As these coordinates are not going to change, a tuple is a fitting data type.

Tuple unpacking

Use the following tuple with cities. 

cities = ("New York", "Los Angeles", "Chicago")

  • Print the first city.
  • Use tuple unpacking and print the resulting variables.

Recap

In this rather short section, we introduced tuples and covered:

  • Mutability vs. immutability
  • How to define a tuple
  • Access elements with indexing
  • ... and tuple unpacking