Tuples

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What are tuples?

• Coordinates (x, y)
• RGB colors (255, 0, 0)
• Database records
• Function return values

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Creating tuples

# Empty tuple
empty = ()

# Tuple with items
point = (3, 5)
colors = ("red", "green", "blue")

# Single item tuple needs comma!
single = (42,)  # Note the comma
not_tuple = (42)  # This is just 42 in parentheses

# Without parentheses (implicit)
coordinates = 10, 20

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Accessing items

point = (3, 5)
colors = ("red", "green", "blue")

# Get items
print(point[0])      # 3
print(colors[-1])    # "blue"

# Slicing works too
print(colors[0:2])   # ("red", "green")

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Tuple unpacking

# Unpack values
point = (3, 5)
x, y = point  # x = 3, y = 5

# Multiple assignment
a, b, c = 1, 2, 3  # Same as (1, 2, 3)

# Swap variables elegantly
x, y = y, x  # Swaps values!

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Tuple Operations

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1. Indexing & Slicing

colors = ("red", "green", "blue", "yellow")
print(colors[1])     # "green"
print(colors[1:3])   # ("green", "blue")

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2. Membership Checking (in)

fruits = ("apple", "banana", "mango")
print("apple" in fruits)  # True
print("cherry" in fruits) # False

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3. Sorting with sorted()

numbers = (5, 2, 8, 1)
sorted_list = sorted(numbers)
print(sorted_list)  # [1, 2, 5, 8] (A list)
sorted_tuple = tuple(sorted_list)
print(sorted_tuple) # (1, 2, 5, 8) (Converted back to a tuple)

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Importance of Tuples

1. Data Integrity (Safety): By making a collection immutable, you guarantee that other parts of your program cannot accidentally modify, append, or delete its values.
2. Performance: Tuples are stored in a single memory block, making them slightly faster to create and access than lists, and they consume less memory.
3. Dictionary Keys: Because tuples are immutable, they are hashable. This means you can use a tuple as a key in a dictionary (e.g. mapping coordinates to locations), which is not possible with lists.

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When to use a Tuple vs a List

• Use a Tuple when:
  • The data is fixed and should never change throughout the execution of the program (e.g., GPS coordinates, RGB values, database config keys).
  • You want to return multiple values from a function.
  • You need to use the collection as a key in a dictionary.
• Use a List when:
  • You have a collection of homogeneous items that will grow, shrink, or change over time (e.g. a shopping cart, a list of users).

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Common mistakes

# Wrong - not a tuple
single = (42)
print(type(single))  # <class 'int'>

# Right - include comma
single = (42,)
print(type(single))  # <class 'tuple'>

# Wrong - tuples are immutable
point = (3, 5)
point[0] = 4  # TypeError!

# Right - create a new tuple
point = (4, point[1])
# Or convert to list, modify, convert back
temp = list(point)
temp[0] = 4
point = tuple(temp)

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Practice & Exercises

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What’s next?