Introduction to Python Arrays

Python Arrays

The array module provides a way to create arrays, which are similar to lists but have a fixed type for their elements.

Arrays can be more efficient in terms of memory usage and performance when dealing with large sequences of homogeneous data.

First, you need to import the array module:

import array

To create an array, you use the array.array() function and specify the type code for the array elements.

The type code determines the type and size of each element in the array.

Here are some commonly used type codes:

• 'b': signed integer of size 1 byte
• 'B': unsigned integer of size 1 byte
• 'i': signed integer of size 2 bytes
• 'I': unsigned integer of size 2 bytes
• 'l': signed integer of size 4 bytes
• 'L': unsigned integer of size 4 bytes
• 'f': floating-point of size 4 bytes
• 'd': floating-point of size 8 bytes

Here's an example that creates an array of integers:

import array

my_array = array.array('i', [1, 2, 3, 4, 5])

In this example:

• We create an array of integers using the 'i' type code.
• The second argument [1, 2, 3, 4, 5] is a list of initial values for the array.

Accessing array element

You can access and manipulate array elements similar to how you work with lists.

As an example:

import array

my_array = array.array('i', [1, 2, 3, 4, 5])

print(my_array[0])  # Output: 1

my_array[2] = 10

print(my_array)  # Output: array('i', [1, 2, 10, 4, 5])

In this example:

• We access the first element of the array using indexing (my_array[0]) and modify the third element by assigning a new value (my_array[2] = 10).

Array Methods

You can also perform various operations on arrays, such as appending elements, removing elements, getting the length, and more. The array module provides methods for these operations.

As an example:

import array

my_array = array.array('i', [1, 2, 3, 4, 5])

my_array.append(6)
print(my_array)  # Output: array('i', [1, 2, 3, 4, 5, 6])

my_array.pop(2)
print(my_array)  # Output: array('i', [1, 2, 4, 5, 6])

length = len(my_array)
print(length)  # Output: 5

In this example:

• We append an element to the array using the append() method, remove an element at index 2 using the pop() method, and get the length of the array using the len() function.

Array Slicing

You can use array slicing to extract a portion of an array. Slicing is done using the colon (:) notation.

As an example:

import array

my_array = array.array('i', [1, 2, 3, 4, 5, 6, 7, 8, 9, 10])

sliced_array = my_array[2:5]
print(sliced_array)  # Output: array('i', [3, 4, 5])

In this example:

• The slice my_array[2:5] extracts elements from index 2 to index 4 (exclusive) and creates a new array.

Concatenation

You can concatenate two arrays using the + operator. The result is a new array that contains the elements of both arrays.

As an example:

import array

array1 = array.array('i', [1, 2, 3])
array2 = array.array('i', [4, 5, 6])

concatenated_array = array1 + array2
print(concatenated_array)  # Output: array('i', [1, 2, 3, 4, 5, 6])

In this example:

• The arrays array1 and array2 are concatenated using the + operator, resulting in a new array.

Iteration

You can iterate over the elements of an array using a loop, such as a for loop.

As an example:

import array

my_array = array.array('i', [1, 2, 3, 4, 5])

for element in my_array:
    print(element)

Array Methods

The array module provides several useful methods for working with arrays.

Here are a few examples:

• insert(index, value): Inserts an element at the specified index.
• remove(value): Removes the first occurrence of the specified value from the array.
• index(value): Returns the index of the first occurrence of the specified value.
• count(value): Returns the number of occurrences of the specified value in the array.
• reverse(): Reverses the order of the elements in the array.
• extend(iterable): Appends elements from the iterable to the end of the array. You can use these methods to manipulate and modify arrays according to your needs.