Difference Between Python List and Array

In this article we are going to discuss about the difference between Python list and array. As you may know both of these are ways to store a collection of items like a bunch of numbers or words but they are not exactly the same. So understanding how they are different will help you select the right one when you are writing your program.

List

Lists are one of the four most commonly used data structures provided by Python. A list is a data structure in python that is mutable and has an ordered sequence of elements. Lists also support negative indexing.

Example

Following is a list of integer values:

# Creating a list
lis= [1,2,3,4,5]

# Printing the list
print(lis)

Output

When you run the program, it will show this output-

[1, 2, 3, 4, 5]

Array

An array is a data structure that holds data in a linear format. Arrays hold a fixed number of elements and these elements should be homogenous (have the same data type). It is also square bracketed, ordered, mutable, and ordered.

Declaring an array by importing the array module.

In Python, we have to import an array module or import NumPy to declare an array.

Example

In this example, we will declare an array by importing the array module.

# Importing the array module
import array as arr

# Declaring an array using the array module
sample_array = arr.array("i", [1, 2, 3, 4])

# Printing the array
print(sample_array)
print(type(sample_array))

Output

After running the program, you will get this result-

array('i', [1, 2, 3, 4])
<type 'array.array'>

Declaring an array by importing Numpy

In this example, we will declare an array by importing the numpy module.

# Importing the numpy module
import numpy as np

# Declaring an array using numpy
sample_array = np.array([1, 2, 3, 4])

# Printing the array
print(sample_array)
print(type(sample_array))

Output

The above code produces the following results-

[1 2 3 4]
<class 'numpy.ndarray'>

Examples to Show the Difference

Here are some of the examples to show the difference between a list and an array in python:

Example 1

In this example, we will show the difference between a list and an array in python.

# Importing the array module
import array as arr
# Importing the numpy module
import numpy as np

# Declaring a list
sample_list = [1, 2, 3, 4]
# Declaring an array using the array module
sample_array = arr.array("i", [1, 2, 3, 4])
# Declaring an array using numpy
sample_array_numpy = np.array([1, 2, 3, 4])

# Printing the list
print("List: ", sample_list)
# Printing the array
print("Array using array module: ", sample_array)
# Printing the array using numpy
print("Array using numpy: ", sample_array_numpy)

Output

This will create the below outcome:

 
List:  [1, 2, 3, 4]
Array using array module:  array('i', [1, 2, 3, 4])
Array using numpy:  [1 2 3 4]

Example 2

In this example, we will declare a list and an array and we will sum the values of list and array separately

my_list = [10, 20, 30]
total_list = sum(my_list)
print("Sum of list:", total_list)

import array
numbers = array.array('i', [5, 10, 15])
total_array = sum(numbers)
print("Sum of array:", total_array)

Output

This will generate the below result:

Sum of list: 60
Sum of array: 30

Differences between a list and an array in python

The following are a few important differences between a list and an array in python -