Arrays

Arrays in Python

An array is a collection of elements stored in a contiguous memory location. In Python, arrays are used to store multiple values of the same data type. Unlike lists, arrays require all elements to be of the same type.

Why Use Arrays Instead of Lists?

• Efficient memory usage: Arrays consume less memory compared to lists.
• Faster operations: Performing mathematical computations on arrays is faster.

Creating an Array in Python

Python does not have built-in support for arrays like C or Java. However, you can use the array module or numpy library.

Using the array Module

To use arrays in Python, you must import the array module.

import array

# Creating an integer array
arr = array.array('i', [10, 20, 30, 40, 50])
print(arr)

Output:

array('i', [10, 20, 30, 40, 50])

Accessing Array Elements

Just like lists, you can access elements using indexing.

print(arr[0])  # First element
print(arr[2])  # Third element
print(arr[-1]) # Last element

Output:

10
30
50

Looping Through an Array

Using for Loop

for item in arr:
    print(item)

Output:

10
20
30
40
50

Using while Loop

i = 0
while i < len(arr):
    print(arr[i])
    i += 1

Output:

10
20
30
40
50

Modifying an Array

Adding Elements

• append(value) – Adds an element at the end.
• insert(index, value) – Adds an element at a specific position.

arr.append(60)       # Add at the end
arr.insert(2, 25)    # Insert 25 at index 2
print(arr)

Output:

array('i', [10, 20, 25, 30, 40, 50, 60])

Removing Elements

• remove(value) – Removes the first occurrence of a value.
• pop(index) – Removes the element at a specific index.

arr.remove(30)  # Remove value 30
arr.pop(1)      # Remove element at index 1
print(arr)

Output:

array('i', [10, 25, 40, 50, 60])

Finding an Element

You can search for an element using index(), which returns the position of the element.

pos = arr.index(40)
print("Index of 40:", pos)

Output:

Index of 40: 2

Sorting an Array

Since the array module does not have a built-in sort() function, we can use sorted().

arr = array.array('i', [50, 10, 40, 30, 20])
sorted_arr = array.array('i', sorted(arr))
print(sorted_arr)

Output:

array('i', [10, 20, 30, 40, 50])

Using NumPy Arrays (Recommended for Large Data)

The NumPy library provides powerful arrays that are faster than the array module

Installing NumPy

pip install numpy

Creating a NumPy Array

import numpy as np

arr = np.array([10, 20, 30, 40, 50])
print(arr)

Output:

[10 20 30 40 50]

Advantages of NumPy Arrays

✅ Faster performance
✅ Supports mathematical operations
✅ Uses less memory