Python Tuples: Comprehensive Theory

Tuples are used to store multiple items in a single variable. A tuple is a collection which is ordered and unchangeable.

1. Characteristics of Tuples

• Ordered: Tuples have a defined order, and that order will not change.
• Unchangeable (Immutable): We cannot change, add, or remove items after the tuple has been created.
• Allow Duplicates: Since tuples are indexed, they can have items with the same value.

2. Creating a Tuple

Tuples are written with round brackets ().

mytuple = ("apple", "banana", "cherry")

Create Tuple With One Item

To create a tuple with only one item, you have to add a comma after the item, otherwise Python will not recognize it as a tuple.

thistuple = ("apple",)
print(type(thistuple)) # <class 'tuple'>

# NOT a tuple
thistuple = ("apple")
print(type(thistuple)) # <class 'str'>

3. Accessing Tuple Items

You can access tuple items by referring to the index number, inside square brackets [].

thistuple = ("apple", "banana", "cherry")
print(thistuple[1]) # Output: banana

Negative Indexing & Slicing

Tuples support negative indexing and slicing just like lists.

• -1 refers to the last item.
• [2:5] refers to items from index 2 to 4.

4. Updating Tuples (Workaround)

Since tuples are unchangeable (immutable), you cannot change them after creation. However, there is a workaround: you can convert the tuple into a list, change the list, and convert the list back into a tuple.

x = ("apple", "banana", "cherry")
y = list(x)
y[1] = "kiwi"
x = tuple(y)

print(x) # ("apple", "kiwi", "cherry")

5. Unpacking Tuples

When we create a tuple, we normally assign values to it. This is called "packing" a tuple. We can also extract the values back into variables. This is called "unpacking".

fruits = ("apple", "banana", "cherry")

(green, yellow, red) = fruits

print(green)  # apple
print(yellow) # banana
print(red)    # cherry

Using Asterisk *

If the number of variables is less than the number of values, you can add an * to the variable name and the values will be assigned to the variable as a list.

fruits = ("apple", "banana", "cherry", "strawberry", "raspberry")

(green, yellow, *red) = fruits

print(green)  # apple
print(yellow) # banana
print(red)    # ['cherry', 'strawberry', 'raspberry']

6. Tuple Methods

Python has two built-in methods that you can use on tuples:

| Method | Description | | :--- | :--- | | count() | Returns the number of times a specified value occurs in a tuple | | index() | Searches the tuple for a specified value and returns the position of where it was found |