Python Program to convert a list into matrix with size of each row increasing by a number

Given a list and a number N, the task here is to write a python program to convert it to matrix where each row has N elements more than previous row elements from list.

Input : test_list = [4, 6, 8, 1, 2, 9, 0, 10, 12, 3, 9, 1], N = 3

Output : [[4, 6, 8], [4, 6, 8, 1, 2, 9], [4, 6, 8, 1, 2, 9, 0, 10, 12], [4, 6, 8, 1, 2, 9, 0, 10, 12, 3, 9, 1]]

Explanation : Each row has 3 elements more than previous row.

Input : test_list = [4, 6, 8, 1, 2, 9, 0, 10, 12, 3, 9, 1], N = 4

Output : [[4, 6, 8, 1], [4, 6, 8, 1, 2, 9, 0, 10], [4, 6, 8, 1, 2, 9, 0, 10, 12, 3, 9, 1]]

Explanation : Each row has 4 elements more than previous row.

Method 1 : Using loop and slicing

In this, we perform task of getting chunks using slicing, and conversion of list into Matrix is done using loop.

Program:

Python3

# initializing list
test_list = [4, 6, 8, 1, 2, 9, 0, 10, 12, 3, 9, 1]

# printing original list
print("The original list is : " + str(test_list))

# initializing N
N = 3

res = []
for idx in range(0, len(test_list) // N):

    # getting incremented chunks
    res.append(test_list[0: (idx + 1) * N])

# printing result
print("Constructed Chunk Matrix : " + str(res))

Output:

The original list is : [4, 6, 8, 1, 2, 9, 0, 10, 12, 3, 9, 1]

Constructed Chunk Matrix : [[4, 6, 8], [4, 6, 8, 1, 2, 9], [4, 6, 8, 1, 2, 9, 0, 10, 12], [4, 6, 8, 1, 2, 9, 0, 10, 12, 3, 9, 1]]

Method 2 : Using list comprehension and list slicing 

In this, we perform task of setting values using list comprehension as a shorthand. Rest all the operations are done similar to above method.

Program:

Python3

# initializing list
test_list = [4, 6, 8, 1, 2, 9, 0, 10, 12, 3, 9, 1]

# printing original list
print("The original list is : " + str(test_list))

# initializing N
N = 3

# getting incremented chunks
# using list comprehension as shorthand
res = [test_list[0: (idx + 1) * N] for idx in range(0, len(test_list) // N)]

# printing result
print("Constructed Chunk Matrix : " + str(res))

Output:

The original list is : [4, 6, 8, 1, 2, 9, 0, 10, 12, 3, 9, 1]

Constructed Chunk Matrix : [[4, 6, 8], [4, 6, 8, 1, 2, 9], [4, 6, 8, 1, 2, 9, 0, 10, 12], [4, 6, 8, 1, 2, 9, 0, 10, 12, 3, 9, 1]]