Python – Convert Matrix to dictionary

Given a Matrix, convert it into dictionary with keys as row number and value as nested list.

Input : test_list = [[5, 6, 7], [8, 3, 2]] Output : {1: [5, 6, 7], 2: [8, 3, 2]} Explanation : Matrix rows are paired with row number in order. Input : test_list = [[5, 6, 7]] Output : {1: [5, 6, 7]} Explanation : Matrix rows are paired with row number in order.

Method #1 : Using dictionary comprehension + range()

The combination of above functions can be used to solve this problem. In this, we perform the task of iteration using dictionary comprehension and range() can be used to perform numbering of rows. 

Python3

# Python3 code to demonstrate working of
# Convert Matrix to dictionary
# Using dictionary comprehension + range()

# initializing list
test_list = [[5, 6, 7], [8, 3, 2], [8, 2, 1]]

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

# using dictionary comprehension for iteration
res = {idx + 1 : test_list[idx] for idx in range(len(test_list))}

# printing result
print("The constructed dictionary : " + str(res))

Output

The original list is : [[5, 6, 7], [8, 3, 2], [8, 2, 1]]
The constructed dictionary : {1: [5, 6, 7], 2: [8, 3, 2], 3: [8, 2, 1]}

Time Complexity: O(n) where n is the number of elements in the list test_list.
Auxiliary Space: O(n), where n is the number of elements in the list test_list.

Method #2 : Using dictionary comprehension + enumerate()

The combination of above functions can be used to solve this problem. In this, dictionary comprehension help in construction of dictionary and enumerate() helps in iteration like range() in above method.

Python3

# Python3 code to demonstrate working of
# Convert Matrix to dictionary
# Using dictionary comprehension + enumerate()

# initializing list
test_list = [[5, 6, 7], [8, 3, 2], [8, 2, 1]]

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

# enumerate used to perform assigning row number
res = {idx: val for idx, val in enumerate(test_list, start = 1)}

# printing result
print("The constructed dictionary : " + str(res))

Output

The original list is : [[5, 6, 7], [8, 3, 2], [8, 2, 1]]
The constructed dictionary : {1: [5, 6, 7], 2: [8, 3, 2], 3: [8, 2, 1]}