4.2 Tuples and Sequence Statistics

Tuples are similar to lists because they store ordered values. The difference is that tuples cannot be modified after creation.

Tuples

Tuples use parentheses (). A one-element tuple must include a trailing comma.

point = (3, 4)
single = (8,)

print(point[0])     # 3
print(point[1])     # 4

Tuples are useful for data that should not be casually changed, such as coordinates, dates, or color values.

Distance between points

import math

p1 = (0, 0)
p2 = (3, 4)

distance = math.sqrt((p1[0] - p2[0]) ** 2 + (p1[1] - p2[1]) ** 2)
print("Distance: %.1f" % distance)

Output:

Distance: 5.0

Sequence statistics

Many built-in functions can work directly on sequences:

• len(): length.
• max(): maximum value.
• min(): minimum value.
• sum(): total.
• any(): true if at least one element is true.
• all(): true only when all elements are true.

lst = [4, 0, 1, 3, 2]
tup = (8, 5, 7, 9)

print(len(lst))     # 5
print(len(tup))     # 4

print(max(lst))     # 4
print(min(tup))     # 5

print(sum(lst))     # 10
print(sum(tup))     # 29

any() and all() are useful for checking groups of conditions.

scores = [85, 92, 78]

print(all(score >= 60 for score in scores))    # True
print(any(score >= 90 for score in scores))    # True