Python Arrays

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Python Arrays (Lists)

An array is a data structure that allows you to store multiple values in a single variable. Instead of creating many separate variables, you can store all values together in one collection.

Instead of creating many separate variables like this:

item1 = "Pen" item2 = "Pencil" item3 = "Eraser"

You can store all values together in one array (which Python calls a list):

stationery = ["Pen", "Pencil", "Eraser"] print(stationery)

['Pen', 'Pencil', 'Eraser']

This makes your code cleaner, easier to manage, and more efficient—especially when working with large amounts of data.

Creating an Array (List)

In Python, arrays are created using square brackets [].

fruits = ["Apple", "Banana", "Mango", "Orange"] print(fruits)

['Apple', 'Banana', 'Mango', 'Orange']

Accessing Array Elements

Each element in an array has an index number, starting from 0.

fruits = ["Apple", "Banana", "Mango", "Orange"] print(fruits[0]) # First element print(fruits[2]) # Third element

Apple Mango

Modifying Array Elements

Array elements can be changed by assigning a new value to a specific index.

fruits = ["Apple", "Banana", "Mango", "Orange"] fruits[1] = "Grapes" print(fruits)

['Apple', 'Grapes', 'Mango', 'Orange']

Length of an Array

Use the len() function to find how many elements are in an array.

fruits = ["Apple", "Banana", "Mango", "Orange"] total_items = len(fruits) print("Total items:", total_items)

Total items: 4

Note: The highest index value is always length - 1.

Looping Through an Array

You can iterate through all elements using a for loop.

fruits = ["Apple", "Banana", "Mango", "Orange"] for fruit in fruits: print("Fruit:", fruit)

Fruit: Apple Fruit: Banana Fruit: Mango Fruit: Orange

Adding Elements to an Array

Use the append() method to add a new element at the end.

fruits = ["Apple", "Banana", "Mango", "Orange"] fruits.append("Pineapple") print(fruits)

['Apple', 'Banana', 'Mango', 'Orange', 'Pineapple']

Removing Elements from an Array

Remove by Index (pop())

fruits = ["Apple", "Banana", "Mango", "Orange"] fruits.pop(2) # Removes the element at index 2 (Mango) print(fruits) # Remove by Value (remove()) fruits.remove("Apple") print(fruits)

['Apple', 'Banana', 'Orange'] ['Banana', 'Orange']

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