Python Subtract Lists Element by Element ( 5 Ways)

In this article, we will be solving a problem statement of python subtract lists element by element. This problem we will be solving in 5 different ways, and discuss each method used to solve this problem in detail.

What is a List in Python? The list is one of the 4 built-in data types in Python used to store data that is mutable, can be ordered, and can be duplicated within the list. The list is created by placing all the elements within the square brackets and separated by commas.

Example :

 list1 = [1,2,3,'john',7.5,3]

Also Read:

• How to remove special characters from string in 4 Ways
• 3 Ways to Convert List to Set

How to subtract lists element by element in python

There are many ways to subtract lists elements wise in python, below we will be discussing 5 ways to do so.

Method 1- Python Subtract lists using the zip() method

The python zip method takes zero or more iterables and returns an iterable object. This iterable object contains the series of tuples containing the element of each iterable given as input.

Syntax –

zip(*iterables)

Iterables – any python iterable like string, list, tuple, or dictionary.

Zip() method return value-

• If we do not pass any parameter it will return an empty iterator
• If multiple iterators are passed, it returns an iterator of tuples, where each tuples tuple contains elements from all iterators passed as input.

Python Code:

list_a = [10, 9, 8, 7]
list_b = [2, 3, 4, 5]
# initalize empty list to stored difference between lists
subtracted_list = []
# iterating on iterator object return by zip() method
for i,j in zip(list_a, list_b):
    subtracted_list.append(i - j)
print("Subtracted List ->",subtracted_list)

Output:-

Subtracted List -> [8, 6, 4, 2]

Method 2- Python Subtract lists element by element using the Naive method

In this method, we will be using python for loop having the range from 0 to the length of the list. And in each iteration, we will subtract lists elements.

Python Code:

# defining lists
list_a = [10, 9, 8, 7]
list_b = [2, 3, 4, 5]
# initialize the subtracted list
subtracted_list = []
# Using for loop to subtract lists
for i in range(len(list_a)):
    subtracted_list.append(list_a[i] - list_b[i])
print("Subtracted List is ->", subtracted_list)

Output:-

Subtracted List is -> [8, 6, 4, 2]

Method 3- Python Subtract lists using the NumPy subtract() method

Numpy in python is used for scientific computing. It consists of multidimensional array objects and methods and functions to process those array objects. To learn about NumPy in python you can read here.

In python to subtract two subtract lists, we can use NumPy subtract() method. The Numpy subtract() method returns the element-wise difference between the two arrays. The Numpy subtract() takes 2 Numpy arrays as input.

Steps to follow to get subtracted list-

1. Define two lists for difference
2. Convert the python lists into a Numpy array by using the Numpy array() method
3. Subtract those arrays using Numpy subtract method.
4. Convert the Numpy array into the python list.
5. Display the output.

Python Code:

# importing numpy package
import numpy as np
# defining list
list_a = [10, 9, 8, 7]
list_b = [2, 3, 4, 5]
# comverting list to numpy array
array_1 = np.array(list_a)
array_2 = np.array(list_b)
# Using numpy subtract function to get element wise subtracted array
subtracted_array = np.subtract(array_1,array_2)
print("Subtracted Numpy array is", subtracted_array)
# Converting Numpy array to list
subtracted_list = list(subtracted_array)
print("Subtracted List is", subtracted_list)

Output:-

Subtracted Numpy array is [8 6 4 2]

Subtracted List is [8, 6, 4, 2]

Also Read: 4 ways to count occurrences in list Python

Method 4- Using List Comprehension

To subtract lists in python we also use list comprehension. In Python, list comprehension is a way to create a new list from existing other iterables like lists, sets, and tuples. We can also say that list comprehension is a shorter version of for loop. To know about list comprehension you can visit this.

Python Code:

# defining list
list_a = [10, 9, 8, 7]
list_b = [2, 3, 4, 5]
# Using list comprehension
subtracted_list =  [x - y for x,y in zip(list_a, list_b)]
print("Subtracted List is", subtracted_list)

Output:-

Subtracted List is [8, 6, 4, 2]

Method 5- Python Subtract lists using the set

In this method, we convert both lists into sets, and use set differences, to find the element-wise difference between the list element. Since we are using the sets, we will get the differences of only all unique elements.

Python code:

# defining list
list_a = [10, 9, 8, 7]
list_b = [2, 3, 4, 5]

# converting list to set
set_a = set(list_a)
set_b = set(list_b)

subtracted_list = list(set_a - set_b)
print("Subtracted List is", subtracted_list)

Output:-

Subtracted List is [8, 9, 10, 7]

Conclusion

Hence we have seen python subtract lists element by element. We have done using zip(), naive method, using list comprehension, and NumPy subtract method.