Tuples and Sets
Fixed groups of values, and collections without duplicates.
Tuples
A tuple is like a list that cannot be changed after it is created. It is written with round brackets. Use tuples for small groups of values that belong together, such as coordinates.
Python
point = (3, 4)
print(point[0], point[1])
rgb = (255, 128, 0)
r, g, b = rgb # unpacking into separate variables
print(f"red={r} green={g} blue={b}")Output
3 4 red=255 green=128 blue=0
Functions often return several values as a tuple:
Python
def min_max(values):
return min(values), max(values)
low, high = min_max([12, 5, 30, 8])
print(low, high)Output
5 30
Sets
A set stores unique values with no particular order. Adding a value that is already there does nothing. Sets are written with curly braces.
Python
visits = [3, 1, 3, 2, 1, 3]
unique = set(visits)
print(unique)
print(len(unique))
print(2 in unique)Output
{1, 2, 3}
3
True
Set operations
Sets support the same operations you learned in maths: union, intersection and difference.
Python
python_club = {101, 102, 103, 104}
chess_club = {103, 104, 105}
print(sorted(python_club | chess_club)) # in either club
print(sorted(python_club & chess_club)) # in both clubs
print(sorted(python_club - chess_club)) # only in the Python clubOutput
[101, 102, 103, 104, 105] [103, 104] [101, 102]
We wrap each result in sorted() because a set does not keep its items in a fixed order; sorting makes the output predictable.