Python | Custom length Matrix
Sometimes, we need to initialize a matrix in Python of variable length from the list containing elements. In this article, we will discuss the variable length method initialization and certain shorthands to do so. Let’s discuss certain ways to perform this.
Method #1 : Using zip() + list comprehension
The zip function combined with the list comprehension can help to achieve this particular task. The zip function can help to zip the counter list with the element list and list comprehension does the work of construction of matrix.
Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.
To begin with, your interview preparations Enhance your Data Structures concepts with the Python DS Course. And to begin with your Machine Learning Journey, join the Machine Learning - Basic Level Course
# Python3 code to demonstrate # Custom length Matrix # using zip() + list comprehension # initializing listtest_list = ['a', 'b', 'c'] # initializing counter list counter_list = [1, 4, 2] # printing original list print ("The original list is : " + str(test_list)) # printing counter list print ("The counter list is : " + str(counter_list)) # using zip() + list comprehension# Custom length Matrix res = [[i] * j for i, j in zip(test_list, counter_list)] # printing resultprint ("The custom length matrix is : " + str(res)) |
The original list is : ['a', 'b', 'c'] The counter list is : [1, 4, 2] The custom length matrix is : [['a'], ['b', 'b', 'b', 'b'], ['c', 'c']]
Method #2 : Using map() + mul operator
This particular problem can also be solved using the inbuilt mul operator which performs multiplication of liked index elements and map function performs the task of formation of matrix.
# Python3 code to demonstrate # Custom length Matrix # using map() + mul operatorfrom operator import mul # initializing listtest_list = ['a', 'b', 'c'] # initializing counter list counter_list = [1, 4, 2] # printing original list print ("The original list is : " + str(test_list)) # printing counter list print ("The counter list is : " + str(counter_list)) # using map() + mul operator# Custom length Matrix res = list(map(mul, [['a'], ['b'], ['c']], counter_list)) # printing resultprint ("The custom length matrix is : " + str(res)) |
The original list is : ['a', 'b', 'c'] The counter list is : [1, 4, 2] The custom length matrix is : [['a'], ['b', 'b', 'b', 'b'], ['c', 'c']]
